diff --git a/src/shrpx-unittest.cc b/src/shrpx-unittest.cc
index 2e156f1d..f65b8002 100644
--- a/src/shrpx-unittest.cc
+++ b/src/shrpx-unittest.cc
@@ -101,14 +101,10 @@ int main(int argc, char *argv[]) {
                    shrpx::test_http2_get_pure_path_component) ||
       !CU_add_test(pSuite, "http2_construct_push_component",
                    shrpx::test_http2_construct_push_component) ||
-      !CU_add_test(pSuite, "downstream_index_request_headers",
-                   shrpx::test_downstream_index_request_headers) ||
-      !CU_add_test(pSuite, "downstream_index_response_headers",
-                   shrpx::test_downstream_index_response_headers) ||
-      !CU_add_test(pSuite, "downstream_get_request_header",
-                   shrpx::test_downstream_get_request_header) ||
-      !CU_add_test(pSuite, "downstream_get_response_header",
-                   shrpx::test_downstream_get_response_header) ||
+      !CU_add_test(pSuite, "downstream_field_store_index_headers",
+                   shrpx::test_downstream_field_store_index_headers) ||
+      !CU_add_test(pSuite, "downstream_field_store_header",
+                   shrpx::test_downstream_field_store_header) ||
       !CU_add_test(pSuite, "downstream_crumble_request_cookie",
                    shrpx::test_downstream_crumble_request_cookie) ||
       !CU_add_test(pSuite, "downstream_assemble_request_cookie",
diff --git a/src/shrpx_client_handler.cc b/src/shrpx_client_handler.cc
index 1bea4e1b..7e7a750d 100644
--- a/src/shrpx_client_handler.cc
+++ b/src/shrpx_client_handler.cc
@@ -812,6 +812,7 @@ std::string construct_absolute_request_uri(const Request &req) {
 void ClientHandler::write_accesslog(Downstream *downstream) {
   nghttp2::ssl::TLSSessionInfo tls_info;
   const auto &req = downstream->request();
+  const auto &resp = downstream->response();
 
   upstream_accesslog(
       get_config()->accesslog_format,
@@ -832,8 +833,7 @@ void ClientHandler::write_accesslog(Downstream *downstream) {
           downstream->get_request_start_time(),      // request_start_time
           std::chrono::high_resolution_clock::now(), // request_end_time
 
-          req.http_major, req.http_minor,
-          downstream->get_response_http_status(),
+          req.http_major, req.http_minor, resp.http_status,
           downstream->get_response_sent_bodylen(), port_.c_str(),
           get_config()->port, get_config()->pid,
       });
diff --git a/src/shrpx_downstream.cc b/src/shrpx_downstream.cc
index 44f5db9e..ddb501a1 100644
--- a/src/shrpx_downstream.cc
+++ b/src/shrpx_downstream.cc
@@ -116,18 +116,15 @@ Downstream::Downstream(Upstream *upstream, MemchunkPool *mcpool,
     : dlnext(nullptr), dlprev(nullptr),
       request_start_time_(std::chrono::high_resolution_clock::now()),
       request_buf_(mcpool), response_buf_(mcpool), request_bodylen_(0),
-      response_bodylen_(0), response_sent_bodylen_(0),
-      response_content_length_(-1), upstream_(upstream), blocked_link_(nullptr),
-      response_headers_sum_(0), request_datalen_(0), response_datalen_(0),
+      response_bodylen_(0), response_sent_bodylen_(0), upstream_(upstream),
+      blocked_link_(nullptr), request_datalen_(0), response_datalen_(0),
       num_retry_(0), stream_id_(stream_id), priority_(priority),
       downstream_stream_id_(-1),
       response_rst_stream_error_code_(NGHTTP2_NO_ERROR),
       request_state_(INITIAL), response_state_(INITIAL),
-      response_http_status_(0), response_major_(1), response_minor_(1),
       dispatch_state_(DISPATCH_NONE), upgraded_(false), chunked_request_(false),
-      chunked_response_(false), response_connection_close_(false),
-      response_header_key_prev_(false), response_trailer_key_prev_(false),
-      expect_final_response_(false), request_pending_(false) {
+      chunked_response_(false), expect_final_response_(false),
+      request_pending_(false) {
 
   ev_timer_init(&upstream_rtimer_, &upstream_rtimeoutcb, 0.,
                 get_config()->stream_read_timeout);
@@ -142,10 +139,6 @@ Downstream::Downstream(Upstream *upstream, MemchunkPool *mcpool,
   upstream_wtimer_.data = this;
   downstream_rtimer_.data = this;
   downstream_wtimer_.data = this;
-
-  http2::init_hdidx(response_hdidx_);
-
-  response_headers_.reserve(32);
 }
 
 Downstream::~Downstream() {
@@ -367,50 +360,6 @@ void append_last_header_value(bool key_prev, size_t &sum, Headers &headers,
 }
 } // namespace
 
-namespace {
-void set_last_header_value(bool &key_prev, size_t &sum, Headers &headers,
-                           const char *data, size_t len) {
-  key_prev = false;
-  sum += len;
-  auto &item = headers.back();
-  item.value.assign(data, len);
-}
-} // namespace
-
-namespace {
-int index_headers(http2::HeaderIndex &hdidx, Headers &headers,
-                  int64_t &content_length) {
-  http2::init_hdidx(hdidx);
-  content_length = -1;
-
-  for (size_t i = 0; i < headers.size(); ++i) {
-    auto &kv = headers[i];
-    util::inp_strlower(kv.name);
-
-    auto token = http2::lookup_token(
-        reinterpret_cast<const uint8_t *>(kv.name.c_str()), kv.name.size());
-    if (token < 0) {
-      continue;
-    }
-
-    kv.token = token;
-    http2::index_header(hdidx, token, i);
-
-    if (token == http2::HD_CONTENT_LENGTH) {
-      auto len = util::parse_uint(kv.value);
-      if (len == -1) {
-        return -1;
-      }
-      if (content_length != -1) {
-        return -1;
-      }
-      content_length = len;
-    }
-  }
-  return 0;
-}
-} // namespace
-
 int FieldStore::index_headers() {
   http2::init_hdidx(hdidx_);
   content_length = -1;
@@ -446,6 +395,10 @@ const Headers::value_type *FieldStore::header(int16_t token) const {
   return http2::get_header(hdidx_, token, headers_);
 }
 
+Headers::value_type *FieldStore::header(int16_t token) {
+  return http2::get_header(hdidx_, token, headers_);
+}
+
 const Headers::value_type *FieldStore::header(const std::string &name) const {
   return get_header_linear(headers_, name);
 }
@@ -585,30 +538,9 @@ int Downstream::end_upload_data() {
   return dconn_->end_upload_data();
 }
 
-const Headers &Downstream::get_response_headers() const {
-  return response_headers_;
-}
-
-Headers &Downstream::get_response_headers() { return response_headers_; }
-
-int Downstream::index_response_headers() {
-  return index_headers(response_hdidx_, response_headers_,
-                       response_content_length_);
-}
-
-const Headers::value_type *
-Downstream::get_response_header(int16_t token) const {
-  return http2::get_header(response_hdidx_, token, response_headers_);
-}
-
-Headers::value_type *Downstream::get_response_header(int16_t token) {
-  return http2::get_header(response_hdidx_, token, response_headers_);
-}
-
 void Downstream::rewrite_location_response_header(
     const std::string &upstream_scheme) {
-  auto hd =
-      http2::get_header(response_hdidx_, http2::HD_LOCATION, response_headers_);
+  auto hd = resp_.fs.header(http2::HD_LOCATION);
   if (!hd) {
     return;
   }
@@ -656,131 +588,18 @@ void Downstream::rewrite_location_response_header(
       }
     }
   }
-  if (!new_uri.empty()) {
-    auto idx = response_hdidx_[http2::HD_LOCATION];
-    response_headers_[idx].value = std::move(new_uri);
+
+  if (new_uri.empty()) {
+    return;
   }
-}
 
-void Downstream::add_response_header(std::string name, std::string value) {
-  add_header(response_header_key_prev_, response_headers_sum_,
-             response_headers_, std::move(name), std::move(value));
-}
-
-void Downstream::set_last_response_header_value(const char *data, size_t len) {
-  set_last_header_value(response_header_key_prev_, response_headers_sum_,
-                        response_headers_, data, len);
-}
-
-void Downstream::add_response_header(std::string name, std::string value,
-                                     int16_t token) {
-  http2::index_header(response_hdidx_, token, response_headers_.size());
-  response_headers_sum_ += name.size() + value.size();
-  response_headers_.emplace_back(std::move(name), std::move(value), false,
-                                 token);
-}
-
-void Downstream::add_response_header(const uint8_t *name, size_t namelen,
-                                     const uint8_t *value, size_t valuelen,
-                                     bool no_index, int16_t token) {
-  http2::index_header(response_hdidx_, token, response_headers_.size());
-  add_header(response_headers_sum_, response_headers_, name, namelen, value,
-             valuelen, no_index, token);
-}
-
-bool Downstream::get_response_header_key_prev() const {
-  return response_header_key_prev_;
-}
-
-void Downstream::append_last_response_header_key(const char *data, size_t len) {
-  append_last_header_key(response_header_key_prev_, response_headers_sum_,
-                         response_headers_, data, len);
-}
-
-void Downstream::append_last_response_header_value(const char *data,
-                                                   size_t len) {
-  append_last_header_value(response_header_key_prev_, response_headers_sum_,
-                           response_headers_, data, len);
-}
-
-void Downstream::clear_response_headers() {
-  Headers().swap(response_headers_);
-  http2::init_hdidx(response_hdidx_);
-}
-
-size_t Downstream::get_response_headers_sum() const {
-  return response_headers_sum_;
-}
-
-const Headers &Downstream::get_response_trailers() const {
-  return response_trailers_;
-}
-
-void Downstream::add_response_trailer(const uint8_t *name, size_t namelen,
-                                      const uint8_t *value, size_t valuelen,
-                                      bool no_index, int16_t token) {
-  add_header(response_headers_sum_, response_trailers_, name, namelen, value,
-             valuelen, no_index, -1);
-}
-
-unsigned int Downstream::get_response_http_status() const {
-  return response_http_status_;
-}
-
-void Downstream::add_response_trailer(std::string name, std::string value) {
-  add_header(response_trailer_key_prev_, response_headers_sum_,
-             response_trailers_, std::move(name), std::move(value));
-}
-
-void Downstream::set_last_response_trailer_value(const char *data, size_t len) {
-  set_last_header_value(response_trailer_key_prev_, response_headers_sum_,
-                        response_trailers_, data, len);
-}
-
-bool Downstream::get_response_trailer_key_prev() const {
-  return response_trailer_key_prev_;
-}
-
-void Downstream::append_last_response_trailer_key(const char *data,
-                                                  size_t len) {
-  append_last_header_key(response_trailer_key_prev_, response_headers_sum_,
-                         response_trailers_, data, len);
-}
-
-void Downstream::append_last_response_trailer_value(const char *data,
-                                                    size_t len) {
-  append_last_header_value(response_trailer_key_prev_, response_headers_sum_,
-                           response_trailers_, data, len);
-}
-
-void Downstream::set_response_http_status(unsigned int status) {
-  response_http_status_ = status;
-}
-
-void Downstream::set_response_major(int major) { response_major_ = major; }
-
-void Downstream::set_response_minor(int minor) { response_minor_ = minor; }
-
-int Downstream::get_response_major() const { return response_major_; }
-
-int Downstream::get_response_minor() const { return response_minor_; }
-
-int Downstream::get_response_version() const {
-  return response_major_ * 100 + response_minor_;
+  (*hd).value = std::move(new_uri);
 }
 
 bool Downstream::get_chunked_response() const { return chunked_response_; }
 
 void Downstream::set_chunked_response(bool f) { chunked_response_ = f; }
 
-bool Downstream::get_response_connection_close() const {
-  return response_connection_close_;
-}
-
-void Downstream::set_response_connection_close(bool f) {
-  response_connection_close_ = f;
-}
-
 int Downstream::on_read() {
   if (!dconn_) {
     DLOG(INFO, this) << "dconn_ is NULL";
@@ -826,14 +645,6 @@ int64_t Downstream::get_response_sent_bodylen() const {
   return response_sent_bodylen_;
 }
 
-int64_t Downstream::get_response_content_length() const {
-  return response_content_length_;
-}
-
-void Downstream::set_response_content_length(int64_t len) {
-  response_content_length_ = len;
-}
-
 bool Downstream::validate_request_bodylen() const {
   if (req_.fs.content_length == -1) {
     return true;
@@ -852,14 +663,14 @@ bool Downstream::validate_request_bodylen() const {
 }
 
 bool Downstream::validate_response_bodylen() const {
-  if (!expect_response_body() || response_content_length_ == -1) {
+  if (!expect_response_body() || resp_.fs.content_length == -1) {
     return true;
   }
 
-  if (response_content_length_ != response_bodylen_) {
+  if (resp_.fs.content_length != response_bodylen_) {
     if (LOG_ENABLED(INFO)) {
       DLOG(INFO, this) << "response invalid bodylen: content-length="
-                       << response_content_length_
+                       << resp_.fs.content_length
                        << ", received=" << response_bodylen_;
     }
     return false;
@@ -874,12 +685,12 @@ int32_t Downstream::get_priority() const { return priority_; }
 
 void Downstream::check_upgrade_fulfilled() {
   if (req_.method == HTTP_CONNECT) {
-    upgraded_ = 200 <= response_http_status_ && response_http_status_ < 300;
+    upgraded_ = 200 <= resp_.http_status && resp_.http_status < 300;
 
     return;
   }
 
-  if (response_http_status_ == 101) {
+  if (resp_.http_status == 101) {
     // TODO Do more strict checking for upgrade headers
     upgraded_ = req_.upgrade_request;
 
@@ -921,23 +732,23 @@ void Downstream::inspect_http1_request() {
 }
 
 void Downstream::inspect_http1_response() {
-  auto idx = response_hdidx_[http2::HD_TRANSFER_ENCODING];
-  if (idx != -1) {
-    response_content_length_ = -1;
-    if (util::strifind(response_headers_[idx].value.c_str(), "chunked")) {
+  auto transfer_encoding = resp_.fs.header(http2::HD_TRANSFER_ENCODING);
+  if (transfer_encoding) {
+    resp_.fs.content_length = -1;
+    if (util::strifind(transfer_encoding->value.c_str(), "chunked")) {
       chunked_response_ = true;
     }
   }
 }
 
 void Downstream::reset_response() {
-  response_http_status_ = 0;
-  response_major_ = 1;
-  response_minor_ = 1;
+  resp_.http_status = 0;
+  resp_.http_major = 1;
+  resp_.http_minor = 1;
 }
 
 bool Downstream::get_non_final_response() const {
-  return !upgraded_ && response_http_status_ / 100 == 1;
+  return !upgraded_ && resp_.http_status / 100 == 1;
 }
 
 bool Downstream::get_upgraded() const { return upgraded_; }
@@ -1004,24 +815,7 @@ size_t Downstream::get_response_datalen() const { return response_datalen_; }
 void Downstream::reset_response_datalen() { response_datalen_ = 0; }
 
 bool Downstream::expect_response_body() const {
-  return http2::expect_response_body(req_.method, response_http_status_);
-}
-
-namespace {
-bool pseudo_header_allowed(const Headers &headers) {
-  if (headers.empty()) {
-    return true;
-  }
-
-  return headers.back().name.c_str()[0] == ':';
-}
-} // namespace
-
-bool Downstream::response_pseudo_header_allowed(int16_t token) const {
-  if (!pseudo_header_allowed(response_headers_)) {
-    return false;
-  }
-  return http2::check_http2_response_pseudo_header(response_hdidx_, token);
+  return http2::expect_response_body(req_.method, resp_.http_status);
 }
 
 namespace {
@@ -1136,7 +930,7 @@ void Downstream::disable_downstream_wtimer() {
   disable_timer(loop, &downstream_wtimer_);
 }
 
-bool Downstream::accesslog_ready() const { return response_http_status_ > 0; }
+bool Downstream::accesslog_ready() const { return resp_.http_status > 0; }
 
 void Downstream::add_retry() { ++num_retry_; }
 
@@ -1176,7 +970,7 @@ BlockedLink *Downstream::detach_blocked_link() {
 bool Downstream::can_detach_downstream_connection() const {
   return dconn_ && response_state_ == Downstream::MSG_COMPLETE &&
          request_state_ == Downstream::MSG_COMPLETE && !upgraded_ &&
-         !response_connection_close_;
+         !resp_.connection_close;
 }
 
 DefaultMemchunks Downstream::pop_response_buf() {
diff --git a/src/shrpx_downstream.h b/src/shrpx_downstream.h
index b13c27e4..577b53c8 100644
--- a/src/shrpx_downstream.h
+++ b/src/shrpx_downstream.h
@@ -73,6 +73,7 @@ public:
   // the beginning.  If no such header is found, returns nullptr.
   // This function must be called after headers are indexed
   const Headers::value_type *header(int16_t token) const;
+  Headers::value_type *header(int16_t token);
   // Returns pointer to the header field with the name |name|.  If no
   // such header is found, returns nullptr.
   const Headers::value_type *header(const std::string &name) const;
@@ -156,6 +157,18 @@ struct Request {
   bool http2_expect_body;
 };
 
+struct Response {
+  Response()
+      : fs(32), http_status(0), http_major(1), http_minor(1),
+        connection_close(false) {}
+
+  FieldStore fs;
+  // HTTP status code
+  unsigned int http_status;
+  int http_major, http_minor;
+  bool connection_close;
+};
+
 class Downstream {
 public:
   Downstream(Upstream *upstream, MemchunkPool *mcpool, int32_t stream_id,
@@ -251,58 +264,17 @@ public:
   bool get_request_pending() const;
   // Returns true if request is ready to be submitted to downstream.
   bool request_submission_ready() const;
+
   // downstream response API
-  const Headers &get_response_headers() const;
-  Headers &get_response_headers();
-  // Lower the response header field names and indexes response
-  // headers.  If there are invalid headers (e.g., multiple
-  // Content-Length with different values), returns -1.
-  int index_response_headers();
-  // Returns pointer to the response header with the name |name|.  If
-  // multiple header have |name| as name, return last occurrence from
-  // the beginning.  If no such header is found, returns nullptr.
-  // This function must be called after response headers are indexed.
-  const Headers::value_type *get_response_header(int16_t token) const;
-  Headers::value_type *get_response_header(int16_t token);
+  const Response &response() const { return resp_; }
+  Response &response() { return resp_; }
+
   // Rewrites the location response header field.
   void rewrite_location_response_header(const std::string &upstream_scheme);
-  void add_response_header(std::string name, std::string value);
-  void set_last_response_header_value(const char *data, size_t len);
 
-  void add_response_header(std::string name, std::string value, int16_t token);
-  void add_response_header(const uint8_t *name, size_t namelen,
-                           const uint8_t *value, size_t valuelen, bool no_index,
-                           int16_t token);
-
-  bool get_response_header_key_prev() const;
-  void append_last_response_header_key(const char *data, size_t len);
-  void append_last_response_header_value(const char *data, size_t len);
-  // Empties response headers.
-  void clear_response_headers();
-
-  size_t get_response_headers_sum() const;
-
-  const Headers &get_response_trailers() const;
-  void add_response_trailer(const uint8_t *name, size_t namelen,
-                            const uint8_t *value, size_t valuelen,
-                            bool no_index, int16_t token);
-  void add_response_trailer(std::string name, std::string value);
-  void set_last_response_trailer_value(const char *data, size_t len);
-  bool get_response_trailer_key_prev() const;
-  void append_last_response_trailer_key(const char *data, size_t len);
-  void append_last_response_trailer_value(const char *data, size_t len);
-
-  unsigned int get_response_http_status() const;
-  void set_response_http_status(unsigned int status);
-  void set_response_major(int major);
-  void set_response_minor(int minor);
-  int get_response_major() const;
-  int get_response_minor() const;
-  int get_response_version() const;
   bool get_chunked_response() const;
   void set_chunked_response(bool f);
-  bool get_response_connection_close() const;
-  void set_response_connection_close(bool f);
+
   void set_response_state(int state);
   int get_response_state() const;
   DefaultMemchunks *get_response_buf();
@@ -311,8 +283,6 @@ public:
   int64_t get_response_bodylen() const;
   void add_response_sent_bodylen(size_t amount);
   int64_t get_response_sent_bodylen() const;
-  int64_t get_response_content_length() const;
-  void set_response_content_length(int64_t len);
   // Validates that received response body length and content-length
   // matches.
   bool validate_response_bodylen() const;
@@ -331,7 +301,6 @@ public:
   void dec_response_datalen(size_t len);
   size_t get_response_datalen() const;
   void reset_response_datalen();
-  bool response_pseudo_header_allowed(int16_t token) const;
 
   // Call this method when there is incoming data in downstream
   // connection.
@@ -402,12 +371,7 @@ public:
 
 private:
   Request req_;
-
-  Headers response_headers_;
-
-  // trailer part.  For HTTP/1.1, trailer part is only included with
-  // chunked encoding.  For HTTP/2, there is no such limit.
-  Headers response_trailers_;
+  Response resp_;
 
   std::chrono::high_resolution_clock::time_point request_start_time_;
 
@@ -434,17 +398,12 @@ private:
   // the length of response body sent to upstream client
   int64_t response_sent_bodylen_;
 
-  // content-length of response body, -1 if it is unknown.
-  int64_t response_content_length_;
-
   Upstream *upstream_;
   std::unique_ptr<DownstreamConnection> dconn_;
 
   // only used by HTTP/2 or SPDY upstream
   BlockedLink *blocked_link_;
 
-  size_t response_headers_sum_;
-
   // The number of bytes not consumed by the application yet.
   size_t request_datalen_;
   size_t response_datalen_;
@@ -460,26 +419,17 @@ private:
   uint32_t response_rst_stream_error_code_;
 
   int request_state_;
-
   int response_state_;
-  unsigned int response_http_status_;
-  int response_major_;
-  int response_minor_;
 
   // only used by HTTP/2 or SPDY upstream
   int dispatch_state_;
 
-  http2::HeaderIndex response_hdidx_;
-
   // true if the connection is upgraded (HTTP Upgrade or CONNECT)
   bool upgraded_;
 
   bool chunked_request_;
-
   bool chunked_response_;
-  bool response_connection_close_;
-  bool response_header_key_prev_;
-  bool response_trailer_key_prev_;
+
   bool expect_final_response_;
   // true if downstream request is pending because backend connection
   // has not been established or should be checked before use;
diff --git a/src/shrpx_downstream_test.cc b/src/shrpx_downstream_test.cc
index e1673880..fb493457 100644
--- a/src/shrpx_downstream_test.cc
+++ b/src/shrpx_downstream_test.cc
@@ -32,17 +32,17 @@
 
 namespace shrpx {
 
-void test_downstream_index_request_headers(void) {
-  Request req;
-  req.fs.add_header("1", "0");
-  req.fs.add_header("2", "1");
-  req.fs.add_header("Charlie", "2");
-  req.fs.add_header("Alpha", "3");
-  req.fs.add_header("Delta", "4");
-  req.fs.add_header("BravO", "5");
-  req.fs.add_header(":method", "6");
-  req.fs.add_header(":authority", "7");
-  req.fs.index_headers();
+void test_downstream_field_store_index_headers(void) {
+  FieldStore fs(0);
+  fs.add_header("1", "0");
+  fs.add_header("2", "1");
+  fs.add_header("Charlie", "2");
+  fs.add_header("Alpha", "3");
+  fs.add_header("Delta", "4");
+  fs.add_header("BravO", "5");
+  fs.add_header(":method", "6");
+  fs.add_header(":authority", "7");
+  fs.index_headers();
 
   auto ans = Headers{{"1", "0"},
                      {"2", "1"},
@@ -52,49 +52,23 @@ void test_downstream_index_request_headers(void) {
                      {"bravo", "5"},
                      {":method", "6"},
                      {":authority", "7"}};
-  CU_ASSERT(ans == req.fs.headers());
+  CU_ASSERT(ans == fs.headers());
 }
 
-void test_downstream_index_response_headers(void) {
-  Downstream d(nullptr, nullptr, 0, 0);
-  d.add_response_header("Charlie", "0");
-  d.add_response_header("Alpha", "1");
-  d.add_response_header("Delta", "2");
-  d.add_response_header("BravO", "3");
-  d.index_response_headers();
-
-  auto ans =
-      Headers{{"charlie", "0"}, {"alpha", "1"}, {"delta", "2"}, {"bravo", "3"}};
-  CU_ASSERT(ans == d.get_response_headers());
-}
-
-void test_downstream_get_request_header(void) {
-  Request req;
-  req.fs.add_header("alpha", "0");
-  req.fs.add_header(":authority", "1");
-  req.fs.add_header("content-length", "2");
-  req.fs.index_headers();
+void test_downstream_field_store_header(void) {
+  FieldStore fs(0);
+  fs.add_header("alpha", "0");
+  fs.add_header(":authority", "1");
+  fs.add_header("content-length", "2");
+  fs.index_headers();
 
   // By token
-  CU_ASSERT(Header(":authority", "1") == *req.fs.header(http2::HD__AUTHORITY));
-  CU_ASSERT(nullptr == req.fs.header(http2::HD__METHOD));
+  CU_ASSERT(Header(":authority", "1") == *fs.header(http2::HD__AUTHORITY));
+  CU_ASSERT(nullptr == fs.header(http2::HD__METHOD));
 
   // By name
-  CU_ASSERT(Header("alpha", "0") == *req.fs.header("alpha"));
-  CU_ASSERT(nullptr == req.fs.header("bravo"));
-}
-
-void test_downstream_get_response_header(void) {
-  Downstream d(nullptr, nullptr, 0, 0);
-  d.add_response_header("alpha", "0");
-  d.add_response_header(":status", "1");
-  d.add_response_header("content-length", "2");
-  d.index_response_headers();
-
-  // By token
-  CU_ASSERT(Header(":status", "1") ==
-            *d.get_response_header(http2::HD__STATUS));
-  CU_ASSERT(nullptr == d.get_response_header(http2::HD__METHOD));
+  CU_ASSERT(Header("alpha", "0") == *fs.header("alpha"));
+  CU_ASSERT(nullptr == fs.header("bravo"));
 }
 
 void test_downstream_crumble_request_cookie(void) {
@@ -154,24 +128,26 @@ void test_downstream_rewrite_location_response_header(void) {
   {
     Downstream d(nullptr, nullptr, 0, 0);
     auto &req = d.request();
+    auto &resp = d.response();
     d.set_request_downstream_host("localhost:3000");
     req.fs.add_header("host", "localhost");
-    d.add_response_header("location", "http://localhost:3000/");
+    resp.fs.add_header("location", "http://localhost:3000/");
     req.fs.index_headers();
-    d.index_response_headers();
+    resp.fs.index_headers();
     d.rewrite_location_response_header("https");
-    auto location = d.get_response_header(http2::HD_LOCATION);
+    auto location = resp.fs.header(http2::HD_LOCATION);
     CU_ASSERT("https://localhost/" == (*location).value);
   }
   {
     Downstream d(nullptr, nullptr, 0, 0);
     auto &req = d.request();
+    auto &resp = d.response();
     d.set_request_downstream_host("localhost");
     req.authority = "localhost";
-    d.add_response_header("location", "http://localhost:3000/");
-    d.index_response_headers();
+    resp.fs.add_header("location", "http://localhost:3000/");
+    resp.fs.index_headers();
     d.rewrite_location_response_header("https");
-    auto location = d.get_response_header(http2::HD_LOCATION);
+    auto location = resp.fs.header(http2::HD_LOCATION);
     CU_ASSERT("https://localhost/" == (*location).value);
   }
 }
diff --git a/src/shrpx_downstream_test.h b/src/shrpx_downstream_test.h
index 67e8f6bd..13b33744 100644
--- a/src/shrpx_downstream_test.h
+++ b/src/shrpx_downstream_test.h
@@ -31,10 +31,8 @@
 
 namespace shrpx {
 
-void test_downstream_index_request_headers(void);
-void test_downstream_index_response_headers(void);
-void test_downstream_get_request_header(void);
-void test_downstream_get_response_header(void);
+void test_downstream_field_store_index_headers(void);
+void test_downstream_field_store_header(void);
 void test_downstream_crumble_request_cookie(void);
 void test_downstream_assemble_request_cookie(void);
 void test_downstream_rewrite_location_response_header(void);
diff --git a/src/shrpx_http2_session.cc b/src/shrpx_http2_session.cc
index 1ec18175..477aeda2 100644
--- a/src/shrpx_http2_session.cc
+++ b/src/shrpx_http2_session.cc
@@ -752,6 +752,8 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
     return 0;
   }
 
+  auto &resp = downstream->response();
+
   switch (frame->hd.type) {
   case NGHTTP2_HEADERS: {
     auto trailer = frame->headers.cat == NGHTTP2_HCAT_HEADERS &&
@@ -759,15 +761,15 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
 
     if (trailer) {
       // just store header fields for trailer part
-      downstream->add_response_trailer(name, namelen, value, valuelen,
-                                       flags & NGHTTP2_NV_FLAG_NO_INDEX, -1);
+      resp.fs.add_trailer(name, namelen, value, valuelen,
+                          flags & NGHTTP2_NV_FLAG_NO_INDEX, -1);
       return 0;
     }
 
     auto token = http2::lookup_token(name, namelen);
 
-    downstream->add_response_header(name, namelen, value, valuelen,
-                                    flags & NGHTTP2_NV_FLAG_NO_INDEX, token);
+    resp.fs.add_header(name, namelen, value, valuelen,
+                       flags & NGHTTP2_NV_FLAG_NO_INDEX, token);
     return 0;
   }
   case NGHTTP2_PUSH_PROMISE: {
@@ -857,18 +859,19 @@ int on_response_headers(Http2Session *http2session, Downstream *downstream,
 
   auto upstream = downstream->get_upstream();
   const auto &req = downstream->request();
+  auto &resp = downstream->response();
 
-  auto &nva = downstream->get_response_headers();
+  auto &nva = resp.fs.headers();
 
   downstream->set_expect_final_response(false);
 
-  auto status = downstream->get_response_header(http2::HD__STATUS);
+  auto status = resp.fs.header(http2::HD__STATUS);
   // libnghttp2 guarantees this exists and can be parsed
   auto status_code = http2::parse_http_status_code(status->value);
 
-  downstream->set_response_http_status(status_code);
-  downstream->set_response_major(2);
-  downstream->set_response_minor(0);
+  resp.http_status = status_code;
+  resp.http_major = 2;
+  resp.http_minor = 0;
 
   if (LOG_ENABLED(INFO)) {
     std::stringstream ss;
@@ -904,7 +907,7 @@ int on_response_headers(Http2Session *http2session, Downstream *downstream,
   downstream->check_upgrade_fulfilled();
 
   if (downstream->get_upgraded()) {
-    downstream->set_response_connection_close(true);
+    resp.connection_close = true;
     // On upgrade sucess, both ends can send data
     if (upstream->resume_read(SHRPX_NO_BUFFER, downstream, 0) != 0) {
       // If resume_read fails, just drop connection. Not ideal.
@@ -917,27 +920,24 @@ int on_response_headers(Http2Session *http2session, Downstream *downstream,
           << "HTTP upgrade success. stream_id=" << frame->hd.stream_id;
     }
   } else {
-    auto content_length =
-        downstream->get_response_header(http2::HD_CONTENT_LENGTH);
+    auto content_length = resp.fs.header(http2::HD_CONTENT_LENGTH);
     if (content_length) {
       // libnghttp2 guarantees this can be parsed
-      auto len = util::parse_uint(content_length->value);
-      downstream->set_response_content_length(len);
+      resp.fs.content_length = util::parse_uint(content_length->value);
     }
 
-    if (downstream->get_response_content_length() == -1 &&
-        downstream->expect_response_body()) {
+    if (resp.fs.content_length == -1 && downstream->expect_response_body()) {
       // Here we have response body but Content-Length is not known in
       // advance.
       if (req.http_major <= 0 || (req.http_major == 1 && req.http_minor == 0)) {
         // We simply close connection for pre-HTTP/1.1 in this case.
-        downstream->set_response_connection_close(true);
+        resp.connection_close = true;
       } else {
         // Otherwise, use chunked encoding to keep upstream connection
         // open.  In HTTP2, we are supporsed not to receive
         // transfer-encoding.
-        downstream->add_response_header("transfer-encoding", "chunked",
-                                        http2::HD_TRANSFER_ENCODING);
+        resp.fs.add_header("transfer-encoding", "chunked",
+                           http2::HD_TRANSFER_ENCODING);
         downstream->set_chunked_response(true);
       }
     }
diff --git a/src/shrpx_http2_upstream.cc b/src/shrpx_http2_upstream.cc
index fd56841f..dc227613 100644
--- a/src/shrpx_http2_upstream.cc
+++ b/src/shrpx_http2_upstream.cc
@@ -1242,6 +1242,7 @@ ssize_t downstream_data_read_callback(nghttp2_session *session,
   assert(body);
 
   auto dconn = downstream->get_downstream_connection();
+  const auto &resp = downstream->response();
 
   if (body->rleft() == 0 && dconn &&
       downstream->get_response_state() != Downstream::MSG_COMPLETE) {
@@ -1263,7 +1264,7 @@ ssize_t downstream_data_read_callback(nghttp2_session *session,
     *data_flags |= NGHTTP2_DATA_FLAG_EOF;
 
     if (!downstream->get_upgraded()) {
-      auto &trailers = downstream->get_response_trailers();
+      const auto &trailers = resp.fs.trailers();
       if (!trailers.empty()) {
         std::vector<nghttp2_nv> nva;
         nva.reserve(trailers.size());
@@ -1303,18 +1304,19 @@ int Http2Upstream::send_reply(Downstream *downstream, const uint8_t *body,
     data_prd_ptr = &data_prd;
   }
 
-  auto &headers = downstream->get_response_headers();
+  const auto &resp = downstream->response();
+
+  const auto &headers = resp.fs.headers();
   auto nva = std::vector<nghttp2_nv>();
   // 2 for :status and server
   nva.reserve(2 + headers.size());
 
   std::string status_code_str;
-  auto response_status_const =
-      http2::stringify_status(downstream->get_response_http_status());
+  auto response_status_const = http2::stringify_status(resp.http_status);
   if (response_status_const) {
     nva.push_back(http2::make_nv_lc_nocopy(":status", response_status_const));
   } else {
-    status_code_str = util::utos(downstream->get_response_http_status());
+    status_code_str = util::utos(resp.http_status);
     nva.push_back(http2::make_nv_ls(":status", status_code_str));
   }
 
@@ -1334,7 +1336,7 @@ int Http2Upstream::send_reply(Downstream *downstream, const uint8_t *body,
     nva.push_back(http2::make_nv_nocopy(kv.name, kv.value, kv.no_index));
   }
 
-  if (!downstream->get_response_header(http2::HD_SERVER)) {
+  if (!resp.fs.header(http2::HD_SERVER)) {
     nva.push_back(
         http2::make_nv_lc_nocopy("server", get_config()->server_name));
   }
@@ -1359,8 +1361,10 @@ int Http2Upstream::send_reply(Downstream *downstream, const uint8_t *body,
 int Http2Upstream::error_reply(Downstream *downstream,
                                unsigned int status_code) {
   int rv;
+  auto &resp = downstream->response();
+
   auto html = http::create_error_html(status_code);
-  downstream->set_response_http_status(status_code);
+  resp.http_status = status_code;
   auto body = downstream->get_response_buf();
   body->append(html.c_str(), html.size());
   downstream->set_response_state(Downstream::MSG_COMPLETE);
@@ -1429,6 +1433,7 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream) {
   int rv;
 
   const auto &req = downstream->request();
+  auto &resp = downstream->response();
 
   if (LOG_ENABLED(INFO)) {
     if (downstream->get_non_final_response()) {
@@ -1462,25 +1467,24 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream) {
   }
 #endif // HAVE_MRUBY
 
-  size_t nheader = downstream->get_response_headers().size();
   auto nva = std::vector<nghttp2_nv>();
   // 4 means :status and possible server, via and x-http2-push header
   // field.
-  nva.reserve(nheader + 4 + get_config()->add_response_headers.size());
+  nva.reserve(resp.fs.headers().size() + 4 +
+              get_config()->add_response_headers.size());
   std::string via_value;
   std::string response_status;
 
-  auto response_status_const =
-      http2::stringify_status(downstream->get_response_http_status());
+  auto response_status_const = http2::stringify_status(resp.http_status);
   if (response_status_const) {
     nva.push_back(http2::make_nv_lc_nocopy(":status", response_status_const));
   } else {
-    response_status = util::utos(downstream->get_response_http_status());
+    response_status = util::utos(resp.http_status);
     nva.push_back(http2::make_nv_ls(":status", response_status));
   }
 
   if (downstream->get_non_final_response()) {
-    http2::copy_headers_to_nva(nva, downstream->get_response_headers());
+    http2::copy_headers_to_nva(nva, resp.fs.headers());
 
     if (LOG_ENABLED(INFO)) {
       log_response_headers(downstream, nva);
@@ -1490,7 +1494,7 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream) {
                                 downstream->get_stream_id(), nullptr,
                                 nva.data(), nva.size(), nullptr);
 
-    downstream->clear_response_headers();
+    resp.fs.clear_headers();
 
     if (rv != 0) {
       ULOG(FATAL, this) << "nghttp2_submit_headers() failed";
@@ -1500,19 +1504,19 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream) {
     return 0;
   }
 
-  http2::copy_headers_to_nva_nocopy(nva, downstream->get_response_headers());
+  http2::copy_headers_to_nva_nocopy(nva, resp.fs.headers());
 
   if (!get_config()->http2_proxy && !get_config()->client_proxy) {
     nva.push_back(
         http2::make_nv_lc_nocopy("server", get_config()->server_name));
   } else {
-    auto server = downstream->get_response_header(http2::HD_SERVER);
+    auto server = resp.fs.header(http2::HD_SERVER);
     if (server) {
       nva.push_back(http2::make_nv_ls_nocopy("server", (*server).value));
     }
   }
 
-  auto via = downstream->get_response_header(http2::HD_VIA);
+  auto via = resp.fs.header(http2::HD_VIA);
   if (get_config()->no_via) {
     if (via) {
       nva.push_back(http2::make_nv_ls_nocopy("via", (*via).value));
@@ -1522,8 +1526,8 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream) {
       via_value = (*via).value;
       via_value += ", ";
     }
-    via_value += http::create_via_header_value(
-        downstream->get_response_major(), downstream->get_response_minor());
+    via_value +=
+        http::create_via_header_value(resp.http_major, resp.http_minor);
     nva.push_back(http2::make_nv_ls("via", via_value));
   }
 
@@ -1575,9 +1579,8 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream) {
       nghttp2_session_get_remote_settings(session_,
                                           NGHTTP2_SETTINGS_ENABLE_PUSH) == 1 &&
       !get_config()->http2_proxy && !get_config()->client_proxy &&
-      (downstream->get_stream_id() % 2) &&
-      downstream->get_response_header(http2::HD_LINK) &&
-      downstream->get_response_http_status() == 200 &&
+      (downstream->get_stream_id() % 2) && resp.fs.header(http2::HD_LINK) &&
+      resp.http_status == 200 &&
       (req.method == HTTP_GET || req.method == HTTP_POST)) {
 
     if (prepare_push_promise(downstream) != 0) {
@@ -1619,9 +1622,11 @@ int Http2Upstream::on_downstream_body_complete(Downstream *downstream) {
     DLOG(INFO, downstream) << "HTTP response completed";
   }
 
+  auto &resp = downstream->response();
+
   if (!downstream->validate_response_bodylen()) {
     rst_stream(downstream, NGHTTP2_PROTOCOL_ERROR);
-    downstream->set_response_connection_close(true);
+    resp.connection_close = true;
     return 0;
   }
 
@@ -1762,13 +1767,14 @@ int Http2Upstream::prepare_push_promise(Downstream *downstream) {
   size_t baselen;
 
   const auto &req = downstream->request();
+  const auto &resp = downstream->response();
 
   rv = http2::get_pure_path_component(&base, &baselen, req.path);
   if (rv != 0) {
     return 0;
   }
 
-  for (auto &kv : downstream->get_response_headers()) {
+  for (auto &kv : resp.fs.headers()) {
     if (kv.token != http2::HD_LINK) {
       continue;
     }
diff --git a/src/shrpx_http_downstream_connection.cc b/src/shrpx_http_downstream_connection.cc
index cac728b9..fee19826 100644
--- a/src/shrpx_http_downstream_connection.cc
+++ b/src/shrpx_http_downstream_connection.cc
@@ -54,9 +54,10 @@ void timeoutcb(struct ev_loop *loop, ev_timer *w, int revents) {
   auto downstream = dconn->get_downstream();
   auto upstream = downstream->get_upstream();
   auto handler = upstream->get_client_handler();
+  auto &resp = downstream->response();
 
   // Do this so that dconn is not pooled
-  downstream->set_response_connection_close(true);
+  resp.connection_close = true;
 
   if (upstream->downstream_error(dconn, Downstream::EVENT_TIMEOUT) != 0) {
     delete handler;
@@ -482,13 +483,14 @@ int htp_hdrs_completecb(http_parser *htp) {
   auto downstream = static_cast<Downstream *>(htp->data);
   auto upstream = downstream->get_upstream();
   const auto &req = downstream->request();
+  auto &resp = downstream->response();
   int rv;
 
-  downstream->set_response_http_status(htp->status_code);
-  downstream->set_response_major(htp->http_major);
-  downstream->set_response_minor(htp->http_minor);
+  resp.http_status = htp->status_code;
+  resp.http_major = htp->http_major;
+  resp.http_minor = htp->http_minor;
 
-  if (downstream->index_response_headers() != 0) {
+  if (resp.fs.index_headers() != 0) {
     downstream->set_response_state(Downstream::MSG_BAD_HEADER);
     return -1;
   }
@@ -500,7 +502,7 @@ int htp_hdrs_completecb(http_parser *htp) {
   if (downstream->get_non_final_response()) {
     // Reset content-length because we reuse same Downstream for the
     // next response.
-    downstream->set_response_content_length(-1);
+    resp.fs.content_length = -1;
     // For non-final response code, we just call
     // on_downstream_header_complete() without changing response
     // state.
@@ -514,13 +516,13 @@ int htp_hdrs_completecb(http_parser *htp) {
     return 1;
   }
 
-  downstream->set_response_connection_close(!http_should_keep_alive(htp));
+  resp.connection_close = !http_should_keep_alive(htp);
   downstream->set_response_state(Downstream::HEADER_COMPLETE);
   downstream->inspect_http1_response();
   if (downstream->get_upgraded()) {
     // content-length must be ignored for upgraded connection.
-    downstream->set_response_content_length(-1);
-    downstream->set_response_connection_close(true);
+    resp.fs.content_length = -1;
+    resp.connection_close = true;
     // transfer-encoding not applied to upgraded connection
     downstream->set_chunked_response(false);
   }
@@ -540,7 +542,7 @@ int htp_hdrs_completecb(http_parser *htp) {
     }
   }
 
-  unsigned int status = downstream->get_response_http_status();
+  auto status = resp.http_status;
   // Ignore the response body. HEAD response may contain
   // Content-Length or Transfer-Encoding: chunked.  Some server send
   // 304 status code with nonzero Content-Length, but without response
@@ -559,18 +561,20 @@ int htp_hdrs_completecb(http_parser *htp) {
 namespace {
 int htp_hdr_keycb(http_parser *htp, const char *data, size_t len) {
   auto downstream = static_cast<Downstream *>(htp->data);
+  auto &resp = downstream->response();
+
   if (downstream->get_response_state() == Downstream::INITIAL) {
-    if (downstream->get_response_header_key_prev()) {
-      downstream->append_last_response_header_key(data, len);
+    if (resp.fs.header_key_prev()) {
+      resp.fs.append_last_header_key(data, len);
     } else {
-      downstream->add_response_header(std::string(data, len), "");
+      resp.fs.add_header(std::string(data, len), "");
     }
   } else {
     // trailer part
-    if (downstream->get_response_trailer_key_prev()) {
-      downstream->append_last_response_trailer_key(data, len);
+    if (resp.fs.trailer_key_prev()) {
+      resp.fs.append_last_trailer_key(data, len);
     } else {
-      downstream->add_response_trailer(std::string(data, len), "");
+      resp.fs.add_trailer(std::string(data, len), "");
     }
   }
   return 0;
@@ -580,18 +584,12 @@ int htp_hdr_keycb(http_parser *htp, const char *data, size_t len) {
 namespace {
 int htp_hdr_valcb(http_parser *htp, const char *data, size_t len) {
   auto downstream = static_cast<Downstream *>(htp->data);
+  auto &resp = downstream->response();
+
   if (downstream->get_response_state() == Downstream::INITIAL) {
-    if (downstream->get_response_header_key_prev()) {
-      downstream->set_last_response_header_value(data, len);
-    } else {
-      downstream->append_last_response_header_value(data, len);
-    }
+    resp.fs.append_last_header_value(data, len);
   } else {
-    if (downstream->get_response_trailer_key_prev()) {
-      downstream->set_last_response_trailer_value(data, len);
-    } else {
-      downstream->append_last_response_trailer_value(data, len);
-    }
+    resp.fs.append_last_trailer_value(data, len);
   }
   return 0;
 }
diff --git a/src/shrpx_https_upstream.cc b/src/shrpx_https_upstream.cc
index 3d9bdc2d..2ca2fe8f 100644
--- a/src/shrpx_https_upstream.cc
+++ b/src/shrpx_https_upstream.cc
@@ -247,6 +247,7 @@ int htp_hdrs_completecb(http_parser *htp) {
   }
   auto downstream = upstream->get_downstream();
   auto &req = downstream->request();
+  auto &resp = downstream->response();
 
   req.http_major = htp->http_major;
   req.http_minor = htp->http_minor;
@@ -325,7 +326,7 @@ int htp_hdrs_completecb(http_parser *htp) {
   auto mruby_ctx = worker->get_mruby_context();
 
   if (mruby_ctx->run_on_request_proc(downstream) != 0) {
-    downstream->set_response_http_status(500);
+    resp.http_status = 500;
     return -1;
   }
 #endif // HAVE_MRUBY
@@ -514,7 +515,7 @@ int HttpsUpstream::on_read() {
     if (htperr == HPE_INVALID_METHOD) {
       status_code = 501;
     } else if (downstream) {
-      status_code = downstream->get_response_http_status();
+      status_code = downstream->response().http_status;
       if (status_code == 0) {
         if (downstream->get_request_state() == Downstream::CONNECT_FAIL) {
           status_code = 503;
@@ -558,6 +559,7 @@ int HttpsUpstream::on_write() {
 
   auto dconn = downstream->get_downstream_connection();
   auto output = downstream->get_response_buf();
+  const auto &resp = downstream->response();
 
   if (output->rleft() == 0 && dconn &&
       downstream->get_response_state() != Downstream::MSG_COMPLETE) {
@@ -578,7 +580,7 @@ int HttpsUpstream::on_write() {
   // We need to postpone detachment until all data are sent so that
   // we can notify nghttp2 library all data consumed.
   if (downstream->get_response_state() == Downstream::MSG_COMPLETE) {
-    if (downstream->get_response_connection_close() ||
+    if (resp.connection_close ||
         downstream->get_request_state() != Downstream::MSG_COMPLETE) {
       // Connection close
       downstream->pop_downstream_connection();
@@ -754,30 +756,30 @@ int HttpsUpstream::downstream_error(DownstreamConnection *dconn, int events) {
 int HttpsUpstream::send_reply(Downstream *downstream, const uint8_t *body,
                               size_t bodylen) {
   const auto &req = downstream->request();
+  auto &resp = downstream->response();
 
   auto connection_close = false;
   if (req.http_major <= 0 || (req.http_major == 1 && req.http_minor == 0)) {
     connection_close = true;
   } else {
-    auto c = downstream->get_response_header(http2::HD_CONNECTION);
+    auto c = resp.fs.header(http2::HD_CONNECTION);
     if (c && util::strieq_l("close", c->value)) {
       connection_close = true;
     }
   }
 
   if (connection_close) {
-    downstream->set_response_connection_close(true);
+    resp.connection_close = true;
     handler_->set_should_close_after_write(true);
   }
 
   auto output = downstream->get_response_buf();
 
   output->append("HTTP/1.1 ");
-  output->append(
-      http2::get_status_string(downstream->get_response_http_status()));
+  output->append(http2::get_status_string(resp.http_status));
   output->append("\r\n");
 
-  for (auto &kv : downstream->get_response_headers()) {
+  for (auto &kv : resp.fs.headers()) {
     if (kv.name.empty() || kv.name[0] == ':') {
       continue;
     }
@@ -787,7 +789,7 @@ int HttpsUpstream::send_reply(Downstream *downstream, const uint8_t *body,
     output->append("\r\n");
   }
 
-  if (!downstream->get_response_header(http2::HD_SERVER)) {
+  if (!resp.fs.header(http2::HD_SERVER)) {
     output->append("Server: ");
     output->append(get_config()->server_name,
                    strlen(get_config()->server_name));
@@ -814,10 +816,12 @@ void HttpsUpstream::error_reply(unsigned int status_code) {
     downstream = get_downstream();
   }
 
-  downstream->set_response_http_status(status_code);
+  auto &resp = downstream->response();
+
+  resp.http_status = status_code;
   // we are going to close connection for both frontend and backend in
   // error condition.  This is safest option.
-  downstream->set_response_connection_close(true);
+  resp.connection_close = true;
   handler_->set_should_close_after_write(true);
 
   auto output = downstream->get_response_buf();
@@ -883,6 +887,7 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
   }
 
   const auto &req = downstream->request();
+  auto &resp = downstream->response();
 
 #ifdef HAVE_MRUBY
   if (!downstream->get_non_final_response()) {
@@ -909,7 +914,7 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
   buf->append(".");
   buf->append(util::utos(req.http_minor));
   buf->append(" ");
-  buf->append(http2::get_status_string(downstream->get_response_http_status()));
+  buf->append(http2::get_status_string(resp.http_status));
   buf->append("\r\n");
 
   if (!get_config()->http2_proxy && !get_config()->client_proxy &&
@@ -918,8 +923,7 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
         get_client_handler()->get_upstream_scheme());
   }
 
-  http2::build_http1_headers_from_headers(buf,
-                                          downstream->get_response_headers());
+  http2::build_http1_headers_from_headers(buf, resp.fs.headers());
 
   if (downstream->get_non_final_response()) {
     buf->append("\r\n");
@@ -928,7 +932,7 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
       log_response_headers(buf);
     }
 
-    downstream->clear_response_headers();
+    resp.fs.clear_headers();
 
     return 0;
   }
@@ -938,12 +942,12 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
   // after graceful shutdown commenced, add connection: close header
   // field.
   if (worker->get_graceful_shutdown()) {
-    downstream->set_response_connection_close(true);
+    resp.connection_close = true;
   }
 
   // We check downstream->get_response_connection_close() in case when
   // the Content-Length is not available.
-  if (!req.connection_close && !downstream->get_response_connection_close()) {
+  if (!req.connection_close && !resp.connection_close) {
     if (req.http_major <= 0 || req.http_minor <= 0) {
       // We add this header for HTTP/1.0 or HTTP/0.9 clients
       buf->append("Connection: Keep-Alive\r\n");
@@ -953,14 +957,14 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
   }
 
   if (!connect_method && downstream->get_upgraded()) {
-    auto connection = downstream->get_response_header(http2::HD_CONNECTION);
+    auto connection = resp.fs.header(http2::HD_CONNECTION);
     if (connection) {
       buf->append("Connection: ");
       buf->append((*connection).value);
       buf->append("\r\n");
     }
 
-    auto upgrade = downstream->get_response_header(http2::HD_UPGRADE);
+    auto upgrade = resp.fs.header(http2::HD_UPGRADE);
     if (upgrade) {
       buf->append("Upgrade: ");
       buf->append((*upgrade).value);
@@ -968,7 +972,7 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
     }
   }
 
-  if (!downstream->get_response_header(http2::HD_ALT_SVC)) {
+  if (!resp.fs.header(http2::HD_ALT_SVC)) {
     // We won't change or alter alt-svc from backend for now
     if (!get_config()->altsvcs.empty()) {
       buf->append("Alt-Svc: ");
@@ -988,7 +992,7 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
     buf->append(get_config()->server_name, strlen(get_config()->server_name));
     buf->append("\r\n");
   } else {
-    auto server = downstream->get_response_header(http2::HD_SERVER);
+    auto server = resp.fs.header(http2::HD_SERVER);
     if (server) {
       buf->append("Server: ");
       buf->append((*server).value);
@@ -996,7 +1000,7 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
     }
   }
 
-  auto via = downstream->get_response_header(http2::HD_VIA);
+  auto via = resp.fs.header(http2::HD_VIA);
   if (get_config()->no_via) {
     if (via) {
       buf->append("Via: ");
@@ -1009,8 +1013,8 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
       buf->append((*via).value);
       buf->append(", ");
     }
-    buf->append(http::create_via_header_value(
-        downstream->get_response_major(), downstream->get_response_minor()));
+    buf->append(
+        http::create_via_header_value(resp.http_major, resp.http_minor));
     buf->append("\r\n");
   }
 
@@ -1055,10 +1059,11 @@ int HttpsUpstream::on_downstream_body(Downstream *downstream,
 
 int HttpsUpstream::on_downstream_body_complete(Downstream *downstream) {
   const auto &req = downstream->request();
+  auto &resp = downstream->response();
 
   if (downstream->get_chunked_response()) {
     auto output = downstream->get_response_buf();
-    auto &trailers = downstream->get_response_trailers();
+    const auto &trailers = resp.fs.trailers();
     if (trailers.empty()) {
       output->append("0\r\n\r\n");
     } else {
@@ -1072,10 +1077,10 @@ int HttpsUpstream::on_downstream_body_complete(Downstream *downstream) {
   }
 
   if (!downstream->validate_response_bodylen()) {
-    downstream->set_response_connection_close(true);
+    resp.connection_close = true;
   }
 
-  if (req.connection_close || downstream->get_response_connection_close()) {
+  if (req.connection_close || resp.connection_close) {
     auto handler = get_client_handler();
     handler->set_should_close_after_write(true);
   }
diff --git a/src/shrpx_mruby.cc b/src/shrpx_mruby.cc
index befd19a2..5b1b3967 100644
--- a/src/shrpx_mruby.cc
+++ b/src/shrpx_mruby.cc
@@ -100,7 +100,7 @@ int MRubyContext::run_app(Downstream *downstream, int phase) {
   }
 
   if (data.response_headers_dirty) {
-    downstream->index_response_headers();
+    downstream->response().fs.index_headers();
   }
 
   return rv;
diff --git a/src/shrpx_mruby_module_response.cc b/src/shrpx_mruby_module_response.cc
index 63cc422e..5b88f879 100644
--- a/src/shrpx_mruby_module_response.cc
+++ b/src/shrpx_mruby_module_response.cc
@@ -49,7 +49,8 @@ namespace {
 mrb_value response_get_http_version_major(mrb_state *mrb, mrb_value self) {
   auto data = static_cast<MRubyAssocData *>(mrb->ud);
   auto downstream = data->downstream;
-  return mrb_fixnum_value(downstream->get_response_major());
+  const auto &resp = downstream->response();
+  return mrb_fixnum_value(resp.http_major);
 }
 } // namespace
 
@@ -57,7 +58,8 @@ namespace {
 mrb_value response_get_http_version_minor(mrb_state *mrb, mrb_value self) {
   auto data = static_cast<MRubyAssocData *>(mrb->ud);
   auto downstream = data->downstream;
-  return mrb_fixnum_value(downstream->get_response_minor());
+  const auto &resp = downstream->response();
+  return mrb_fixnum_value(resp.http_minor);
 }
 } // namespace
 
@@ -65,8 +67,8 @@ namespace {
 mrb_value response_get_status(mrb_state *mrb, mrb_value self) {
   auto data = static_cast<MRubyAssocData *>(mrb->ud);
   auto downstream = data->downstream;
-
-  return mrb_fixnum_value(downstream->get_response_http_status());
+  const auto &resp = downstream->response();
+  return mrb_fixnum_value(resp.http_status);
 }
 } // namespace
 
@@ -74,6 +76,7 @@ namespace {
 mrb_value response_set_status(mrb_state *mrb, mrb_value self) {
   auto data = static_cast<MRubyAssocData *>(mrb->ud);
   auto downstream = data->downstream;
+  auto &resp = downstream->response();
 
   mrb_int status;
   mrb_get_args(mrb, "i", &status);
@@ -83,7 +86,7 @@ mrb_value response_set_status(mrb_state *mrb, mrb_value self) {
               "invalid status; it should be [200, 999], inclusive");
   }
 
-  downstream->set_response_http_status(status);
+  resp.http_status = status;
 
   return self;
 }
@@ -93,7 +96,9 @@ namespace {
 mrb_value response_get_headers(mrb_state *mrb, mrb_value self) {
   auto data = static_cast<MRubyAssocData *>(mrb->ud);
   auto downstream = data->downstream;
-  return create_headers_hash(mrb, downstream->get_response_headers());
+  const auto &resp = downstream->response();
+
+  return create_headers_hash(mrb, resp.fs.headers());
 }
 } // namespace
 
@@ -101,6 +106,7 @@ namespace {
 mrb_value response_mod_header(mrb_state *mrb, mrb_value self, bool repl) {
   auto data = static_cast<MRubyAssocData *>(mrb->ud);
   auto downstream = data->downstream;
+  auto &resp = downstream->response();
 
   mrb_value key, values;
   mrb_get_args(mrb, "oo", &key, &values);
@@ -113,7 +119,7 @@ mrb_value response_mod_header(mrb_state *mrb, mrb_value self, bool repl) {
 
   if (repl) {
     size_t p = 0;
-    auto &headers = downstream->get_response_headers();
+    auto &headers = resp.fs.headers();
     for (size_t i = 0; i < headers.size(); ++i) {
       auto &hd = headers[i];
       if (util::streq(std::begin(hd.name), hd.name.size(), RSTRING_PTR(key),
@@ -131,14 +137,12 @@ mrb_value response_mod_header(mrb_state *mrb, mrb_value self, bool repl) {
     auto n = mrb_ary_len(mrb, values);
     for (int i = 0; i < n; ++i) {
       auto value = mrb_ary_entry(values, i);
-      downstream->add_response_header(
-          std::string(RSTRING_PTR(key), RSTRING_LEN(key)),
-          std::string(RSTRING_PTR(value), RSTRING_LEN(value)));
+      resp.fs.add_header(std::string(RSTRING_PTR(key), RSTRING_LEN(key)),
+                         std::string(RSTRING_PTR(value), RSTRING_LEN(value)));
     }
   } else if (!mrb_nil_p(values)) {
-    downstream->add_response_header(
-        std::string(RSTRING_PTR(key), RSTRING_LEN(key)),
-        std::string(RSTRING_PTR(values), RSTRING_LEN(values)));
+    resp.fs.add_header(std::string(RSTRING_PTR(key), RSTRING_LEN(key)),
+                       std::string(RSTRING_PTR(values), RSTRING_LEN(values)));
   }
 
   data->response_headers_dirty = true;
@@ -163,8 +167,9 @@ namespace {
 mrb_value response_clear_headers(mrb_state *mrb, mrb_value self) {
   auto data = static_cast<MRubyAssocData *>(mrb->ud);
   auto downstream = data->downstream;
+  auto &resp = downstream->response();
 
-  downstream->clear_response_headers();
+  resp.fs.clear_headers();
 
   return mrb_nil_value();
 }
@@ -174,6 +179,7 @@ namespace {
 mrb_value response_return(mrb_state *mrb, mrb_value self) {
   auto data = static_cast<MRubyAssocData *>(mrb->ud);
   auto downstream = data->downstream;
+  auto &resp = downstream->response();
   int rv;
 
   if (downstream->get_response_state() == Downstream::MSG_COMPLETE) {
@@ -187,12 +193,12 @@ mrb_value response_return(mrb_state *mrb, mrb_value self) {
   const uint8_t *body = nullptr;
   size_t bodylen = 0;
 
-  if (downstream->get_response_http_status() == 0) {
-    downstream->set_response_http_status(200);
+  if (resp.http_status == 0) {
+    resp.http_status = 200;
   }
 
   if (data->response_headers_dirty) {
-    downstream->index_response_headers();
+    resp.fs.index_headers();
     data->response_headers_dirty = false;
   }
 
@@ -201,21 +207,20 @@ mrb_value response_return(mrb_state *mrb, mrb_value self) {
     bodylen = vallen;
   }
 
-  auto cl = downstream->get_response_header(http2::HD_CONTENT_LENGTH);
+  auto cl = resp.fs.header(http2::HD_CONTENT_LENGTH);
   if (cl) {
     cl->value = util::utos(bodylen);
   } else {
-    downstream->add_response_header("content-length", util::utos(bodylen),
-                                    http2::HD_CONTENT_LENGTH);
+    resp.fs.add_header("content-length", util::utos(bodylen),
+                       http2::HD_CONTENT_LENGTH);
   }
-  downstream->set_response_content_length(bodylen);
+  resp.fs.content_length = bodylen;
 
-  auto date = downstream->get_response_header(http2::HD_DATE);
+  auto date = resp.fs.header(http2::HD_DATE);
   if (!date) {
     auto lgconf = log_config();
     lgconf->update_tstamp(std::chrono::system_clock::now());
-    downstream->add_response_header("date", lgconf->time_http_str,
-                                    http2::HD_DATE);
+    resp.fs.add_header("date", lgconf->time_http_str, http2::HD_DATE);
   }
 
   auto upstream = downstream->get_upstream();
diff --git a/src/shrpx_spdy_upstream.cc b/src/shrpx_spdy_upstream.cc
index 5f112991..0fb7fd59 100644
--- a/src/shrpx_spdy_upstream.cc
+++ b/src/shrpx_spdy_upstream.cc
@@ -820,10 +820,11 @@ int SpdyUpstream::send_reply(Downstream *downstream, const uint8_t *body,
     data_prd_ptr = &data_prd;
   }
 
-  auto status_string =
-      http2::get_status_string(downstream->get_response_http_status());
+  const auto &resp = downstream->response();
 
-  auto &headers = downstream->get_response_headers();
+  auto status_string = http2::get_status_string(resp.http_status);
+
+  const auto &headers = resp.fs.headers();
 
   auto nva = std::vector<const char *>();
   // 3 for :status, :version and server
@@ -849,7 +850,7 @@ int SpdyUpstream::send_reply(Downstream *downstream, const uint8_t *body,
     nva.push_back(kv.value.c_str());
   }
 
-  if (!downstream->get_response_header(http2::HD_SERVER)) {
+  if (!resp.fs.header(http2::HD_SERVER)) {
     nva.push_back("server");
     nva.push_back(get_config()->server_name);
   }
@@ -876,8 +877,10 @@ int SpdyUpstream::send_reply(Downstream *downstream, const uint8_t *body,
 int SpdyUpstream::error_reply(Downstream *downstream,
                               unsigned int status_code) {
   int rv;
+  auto &resp = downstream->response();
+
   auto html = http::create_error_html(status_code);
-  downstream->set_response_http_status(status_code);
+  resp.http_status = status_code;
   auto body = downstream->get_response_buf();
   body->append(html.c_str(), html.size());
   downstream->set_response_state(Downstream::MSG_COMPLETE);
@@ -938,11 +941,13 @@ void SpdyUpstream::remove_downstream(Downstream *downstream) {
 // WARNING: Never call directly or indirectly spdylay_session_send or
 // spdylay_session_recv. These calls may delete downstream.
 int SpdyUpstream::on_downstream_header_complete(Downstream *downstream) {
+  auto &resp = downstream->response();
+
   if (downstream->get_non_final_response()) {
     // SPDY does not support non-final response.  We could send it
     // with HEADERS and final response in SYN_REPLY, but it is not
     // official way.
-    downstream->clear_response_headers();
+    resp.fs.clear_headers();
 
     return 0;
   }
@@ -974,20 +979,20 @@ int SpdyUpstream::on_downstream_header_complete(Downstream *downstream) {
       !get_config()->no_location_rewrite) {
     downstream->rewrite_location_response_header(req.scheme);
   }
-  size_t nheader = downstream->get_response_headers().size();
+
   // 8 means server, :status, :version and possible via header field.
   auto nv = make_unique<const char *[]>(
-      nheader * 2 + 8 + get_config()->add_response_headers.size() * 2 + 1);
+      resp.fs.headers().size() * 2 + 8 +
+      get_config()->add_response_headers.size() * 2 + 1);
 
   size_t hdidx = 0;
   std::string via_value;
-  std::string status_string =
-      http2::get_status_string(downstream->get_response_http_status());
+  auto status_string = http2::get_status_string(resp.http_status);
   nv[hdidx++] = ":status";
   nv[hdidx++] = status_string.c_str();
   nv[hdidx++] = ":version";
   nv[hdidx++] = "HTTP/1.1";
-  for (auto &hd : downstream->get_response_headers()) {
+  for (auto &hd : resp.fs.headers()) {
     if (hd.name.empty() || hd.name.c_str()[0] == ':') {
       continue;
     }
@@ -1009,14 +1014,14 @@ int SpdyUpstream::on_downstream_header_complete(Downstream *downstream) {
     nv[hdidx++] = "server";
     nv[hdidx++] = get_config()->server_name;
   } else {
-    auto server = downstream->get_response_header(http2::HD_SERVER);
+    auto server = resp.fs.header(http2::HD_SERVER);
     if (server) {
       nv[hdidx++] = "server";
       nv[hdidx++] = server->value.c_str();
     }
   }
 
-  auto via = downstream->get_response_header(http2::HD_VIA);
+  auto via = resp.fs.header(http2::HD_VIA);
   if (get_config()->no_via) {
     if (via) {
       nv[hdidx++] = "via";
@@ -1027,8 +1032,8 @@ int SpdyUpstream::on_downstream_header_complete(Downstream *downstream) {
       via_value = via->value;
       via_value += ", ";
     }
-    via_value += http::create_via_header_value(
-        downstream->get_response_major(), downstream->get_response_minor());
+    via_value +=
+        http::create_via_header_value(resp.http_major, resp.http_minor);
     nv[hdidx++] = "via";
     nv[hdidx++] = via_value.c_str();
   }
@@ -1086,9 +1091,11 @@ int SpdyUpstream::on_downstream_body_complete(Downstream *downstream) {
     DLOG(INFO, downstream) << "HTTP response completed";
   }
 
+  auto &resp = downstream->response();
+
   if (!downstream->validate_response_bodylen()) {
     rst_stream(downstream, SPDYLAY_PROTOCOL_ERROR);
-    downstream->set_response_connection_close(true);
+    resp.connection_close = true;
     return 0;
   }