diff --git a/ChangeLog b/ChangeLog
index 82ca771..23d35de 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -45,6 +45,10 @@ It is freed with the match data block.
 different in different environments and so cannot be included in the standard 
 tests.
 
+12. Created a test for pcre2_match() heap processing that is not part of the 
+tests run by 'make check', but can be run manually. The current output is from 
+a 64-bit system.
+
 
 Version 10.40 15-April-2022
 ---------------------------
diff --git a/RunTest b/RunTest
index 9b67870..8fb6a2c 100755
--- a/RunTest
+++ b/RunTest
@@ -17,8 +17,16 @@
 # individual test numbers, ranges of tests such as 3-6 or 3- (meaning 3 to the
 # end), or a number preceded by ~ to exclude a test. For example, "3-15 ~10"
 # runs tests 3 to 15, excluding test 10, and just "~10" runs all the tests
-# except test 10. Whatever order the arguments are in, the tests are always run
-# in numerical order.
+# except test 10. Whatever order the arguments are in, these tests are always
+# run in numerical order.
+#
+# If no specific tests are selected (which is the case when this script is run
+# via 'make check') the default is to run all the numbered tests.
+#
+# There may also be named (as well as numbered) tests for special purposes. At
+# present there is just one, called "heap". This test's output contains the
+# sizes of heap frames and frame vectors, which depend on the environment. It
+# is therefore not run unless explicitly requested.
 #
 # Inappropriate tests are automatically skipped (with a comment to say so). For
 # example, if JIT support is not compiled, test 16 is skipped, whereas if JIT
@@ -82,6 +90,7 @@ title24="Test 24: Non-UTF pattern conversion tests"
 title25="Test 25: UTF pattern conversion tests"
 title26="Test 26: Auto-generated unicode property tests"
 maxtest=26
+titleheap="Test 'heap': Environment-specific heap tests"
 
 if [ $# -eq 1 -a "$1" = "list" ]; then
   echo $title0
@@ -111,6 +120,11 @@ if [ $# -eq 1 -a "$1" = "list" ]; then
   echo $title24
   echo $title25
   echo $title26
+  echo ""
+  echo $titleheap
+  echo ""
+  echo "Numbered tests are automatically run if nothing selected."
+  echo "Named tests must be explicitly selected."
   exit 0
 fi
 
@@ -241,6 +255,7 @@ do23=no
 do24=no
 do25=no
 do26=no
+doheap=no
 
 while [ $# -gt 0 ] ; do
   case $1 in
@@ -271,6 +286,7 @@ while [ $# -gt 0 ] ; do
    24) do24=yes;;
    25) do25=yes;;
    26) do26=yes;;
+ heap) doheap=yes;;
    -8) arg8=yes;;
   -16) arg16=yes;;
   -32) arg32=yes;;
@@ -412,8 +428,8 @@ if [ $jit -ne 0 -a "$nojit" != "yes" ] ; then
   fi
 fi
 
-# If no specific tests were requested, select all. Those that are not
-# relevant will be automatically skipped.
+# If no specific tests were requested, select all the numbered tests. Those
+# that are not relevant will be automatically skipped.
 
 if [ $do0  = no -a $do1  = no -a $do2  = no -a $do3  = no -a \
      $do4  = no -a $do5  = no -a $do6  = no -a $do7  = no -a \
@@ -421,7 +437,7 @@ if [ $do0  = no -a $do1  = no -a $do2  = no -a $do3  = no -a \
      $do12 = no -a $do13 = no -a $do14 = no -a $do15 = no -a \
      $do16 = no -a $do17 = no -a $do18 = no -a $do19 = no -a \
      $do20 = no -a $do21 = no -a $do22 = no -a $do23 = no -a \
-     $do24 = no -a $do25 = no -a $do26 = no \
+     $do24 = no -a $do25 = no -a $do26 = no -a $doheap = no \
    ]; then
   do0=yes
   do1=yes
@@ -882,6 +898,15 @@ for bmode in "$test8" "$test16" "$test32"; do
     fi
   fi
 
+  # Manually selected heap tests - output may vary in different environments,
+  # which is why that are not automatically run.
+
+  if [ $doheap = yes ] ; then
+    echo $titleheap
+    $sim $valgrind ./pcre2test -q $setstack $bmode $testdata/testinputheap testtry
+    checkresult $? heap-$bits ""
+  fi
+
 # End of loop for 8/16/32-bit tests
 done
 
diff --git a/src/pcre2test.c b/src/pcre2test.c
index 7f68b1d..7f44de7 100644
--- a/src/pcre2test.c
+++ b/src/pcre2test.c
@@ -1246,19 +1246,19 @@ are supported. */
 
 #define PCRE2_MATCH_DATA_CREATE(a,b,c) \
   if (test_mode == PCRE8_MODE) \
-    G(a,8) = pcre2_match_data_create_8(b,c); \
+    G(a,8) = pcre2_match_data_create_8(b,G(c,8)); \
   else if (test_mode == PCRE16_MODE) \
-    G(a,16) = pcre2_match_data_create_16(b,c); \
+    G(a,16) = pcre2_match_data_create_16(b,G(c,16)); \
   else \
-    G(a,32) = pcre2_match_data_create_32(b,c)
+    G(a,32) = pcre2_match_data_create_32(b,G(c,32))
 
 #define PCRE2_MATCH_DATA_CREATE_FROM_PATTERN(a,b,c) \
   if (test_mode == PCRE8_MODE) \
-    G(a,8) = pcre2_match_data_create_from_pattern_8(G(b,8),c); \
+    G(a,8) = pcre2_match_data_create_from_pattern_8(G(b,8),G(c,8)); \
   else if (test_mode == PCRE16_MODE) \
-    G(a,16) = pcre2_match_data_create_from_pattern_16(G(b,16),c); \
+    G(a,16) = pcre2_match_data_create_from_pattern_16(G(b,16),G(c,16)); \
   else \
-    G(a,32) = pcre2_match_data_create_from_pattern_32(G(b,32),c)
+    G(a,32) = pcre2_match_data_create_from_pattern_32(G(b,32),G(c,32))
 
 #define PCRE2_MATCH_DATA_FREE(a) \
   if (test_mode == PCRE8_MODE) \
@@ -1766,15 +1766,15 @@ the three different cases. */
 
 #define PCRE2_MATCH_DATA_CREATE(a,b,c) \
   if (test_mode == G(G(PCRE,BITONE),_MODE)) \
-    G(a,BITONE) = G(pcre2_match_data_create_,BITONE)(b,c); \
+    G(a,BITONE) = G(pcre2_match_data_create_,BITONE)(b,G(c,BITONE)); \
   else \
-    G(a,BITTWO) = G(pcre2_match_data_create_,BITTWO)(b,c)
+    G(a,BITTWO) = G(pcre2_match_data_create_,BITTWO)(b,G(c,BITTWO))
 
 #define PCRE2_MATCH_DATA_CREATE_FROM_PATTERN(a,b,c) \
   if (test_mode == G(G(PCRE,BITONE),_MODE)) \
-    G(a,BITONE) = G(pcre2_match_data_create_from_pattern_,BITONE)(G(b,BITONE),c); \
+    G(a,BITONE) = G(pcre2_match_data_create_from_pattern_,BITONE)(G(b,BITONE),G(c,BITONE)); \
   else \
-    G(a,BITTWO) = G(pcre2_match_data_create_from_pattern_,BITTWO)(G(b,BITTWO),c)
+    G(a,BITTWO) = G(pcre2_match_data_create_from_pattern_,BITTWO)(G(b,BITTWO),G(c,BITTWO))
 
 #define PCRE2_MATCH_DATA_FREE(a) \
   if (test_mode == G(G(PCRE,BITONE),_MODE)) \
@@ -2074,9 +2074,9 @@ the three different cases. */
 #define PCRE2_MAKETABLES(a) a = pcre2_maketables_8(NULL)
 #define PCRE2_MATCH(a,b,c,d,e,f,g,h) \
   a = pcre2_match_8(G(b,8),(PCRE2_SPTR8)c,d,e,f,G(g,8),h)
-#define PCRE2_MATCH_DATA_CREATE(a,b,c) G(a,8) = pcre2_match_data_create_8(b,c)
+#define PCRE2_MATCH_DATA_CREATE(a,b,c) G(a,8) = pcre2_match_data_create_8(b,G(c,8))
 #define PCRE2_MATCH_DATA_CREATE_FROM_PATTERN(a,b,c) \
-  G(a,8) = pcre2_match_data_create_from_pattern_8(G(b,8),c)
+  G(a,8) = pcre2_match_data_create_from_pattern_8(G(b,8),G(c,8))
 #define PCRE2_MATCH_DATA_FREE(a) pcre2_match_data_free_8(G(a,8))
 #define PCRE2_PATTERN_CONVERT(a,b,c,d,e,f,g) a = pcre2_pattern_convert_8(G(b,8),c,d,(PCRE2_UCHAR8 **)e,f,G(g,8))
 #define PCRE2_PATTERN_INFO(a,b,c,d) a = pcre2_pattern_info_8(G(b,8),c,d)
@@ -2181,9 +2181,9 @@ the three different cases. */
 #define PCRE2_MAKETABLES(a) a = pcre2_maketables_16(NULL)
 #define PCRE2_MATCH(a,b,c,d,e,f,g,h) \
   a = pcre2_match_16(G(b,16),(PCRE2_SPTR16)c,d,e,f,G(g,16),h)
-#define PCRE2_MATCH_DATA_CREATE(a,b,c) G(a,16) = pcre2_match_data_create_16(b,c)
+#define PCRE2_MATCH_DATA_CREATE(a,b,c) G(a,16) = pcre2_match_data_create_16(b,G(c,16))
 #define PCRE2_MATCH_DATA_CREATE_FROM_PATTERN(a,b,c) \
-  G(a,16) = pcre2_match_data_create_from_pattern_16(G(b,16),c)
+  G(a,16) = pcre2_match_data_create_from_pattern_16(G(b,16),G(c,16))
 #define PCRE2_MATCH_DATA_FREE(a) pcre2_match_data_free_16(G(a,16))
 #define PCRE2_PATTERN_CONVERT(a,b,c,d,e,f,g) a = pcre2_pattern_convert_16(G(b,16),c,d,(PCRE2_UCHAR16 **)e,f,G(g,16))
 #define PCRE2_PATTERN_INFO(a,b,c,d) a = pcre2_pattern_info_16(G(b,16),c,d)
@@ -2288,9 +2288,9 @@ the three different cases. */
 #define PCRE2_MAKETABLES(a) a = pcre2_maketables_32(NULL)
 #define PCRE2_MATCH(a,b,c,d,e,f,g,h) \
   a = pcre2_match_32(G(b,32),(PCRE2_SPTR32)c,d,e,f,G(g,32),h)
-#define PCRE2_MATCH_DATA_CREATE(a,b,c) G(a,32) = pcre2_match_data_create_32(b,c)
+#define PCRE2_MATCH_DATA_CREATE(a,b,c) G(a,32) = pcre2_match_data_create_32(b,G(c,32))
 #define PCRE2_MATCH_DATA_CREATE_FROM_PATTERN(a,b,c) \
-  G(a,32) = pcre2_match_data_create_from_pattern_32(G(b,32),c)
+  G(a,32) = pcre2_match_data_create_from_pattern_32(G(b,32),G(c,32))
 #define PCRE2_MATCH_DATA_FREE(a) pcre2_match_data_free_32(G(a,32))
 #define PCRE2_PATTERN_CONVERT(a,b,c,d,e,f,g) a = pcre2_pattern_convert_32(G(b,32),c,d,(PCRE2_UCHAR32 **)e,f,G(g,32))
 #define PCRE2_PATTERN_INFO(a,b,c,d) a = pcre2_pattern_info_32(G(b,32),c,d)
@@ -2784,7 +2784,7 @@ return block;
 static void my_free(void *block, void *data)
 {
 (void)data;
-if (show_memory)
+if (show_memory && block != NULL)
   {
   uint32_t i, j;
   BOOL found = FALSE;
@@ -7318,7 +7318,8 @@ causes a new match data block to be obtained that exactly fits the pattern. */
 if (dat_datctl.oveccount == 0)
   {
   PCRE2_MATCH_DATA_FREE(match_data);
-  PCRE2_MATCH_DATA_CREATE_FROM_PATTERN(match_data, compiled_code, NULL);
+  PCRE2_MATCH_DATA_CREATE_FROM_PATTERN(match_data, compiled_code,
+    general_context);
   PCRE2_GET_OVECTOR_COUNT(max_oveccount, match_data);
   }
 else if (dat_datctl.oveccount <= max_oveccount)
@@ -7329,7 +7330,7 @@ else
   {
   max_oveccount = dat_datctl.oveccount;
   PCRE2_MATCH_DATA_FREE(match_data);
-  PCRE2_MATCH_DATA_CREATE(match_data, max_oveccount, NULL);
+  PCRE2_MATCH_DATA_CREATE(match_data, max_oveccount, general_context);
   }
 
 if (CASTVAR(void *, match_data) == NULL)
diff --git a/testdata/testinputheap b/testdata/testinputheap
new file mode 100644
index 0000000..ee165e1
--- /dev/null
+++ b/testdata/testinputheap
@@ -0,0 +1,13 @@
+#pattern framesize, memory
+
+/abcd/
+    abcd\=memory
+    abcd\=find_limits
+
+/(((((((((((((((((((((((((((((( (^abc|xyz){1,20}$  ))))))))))))))))))))))))))))))/x
+    abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcX\=memory
+    abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcX\=find_limits
+
+/ab(cd)/
+    abcd\=memory
+    abcd\=memory,ovector=0 
diff --git a/testdata/testoutputheap-16 b/testdata/testoutputheap-16
new file mode 100644
index 0000000..41855e4
--- /dev/null
+++ b/testdata/testoutputheap-16
@@ -0,0 +1,40 @@
+#pattern framesize, memory
+
+/abcd/
+Memory allocation (code space): 26
+Frame size for pcre2_match(): 128
+    abcd\=memory
+malloc  20480
+ 0: abcd
+    abcd\=find_limits
+Minimum heap limit = 1
+Minimum match limit = 2
+Minimum depth limit = 2
+ 0: abcd
+
+/(((((((((((((((((((((((((((((( (^abc|xyz){1,20}$  ))))))))))))))))))))))))))))))/x
+Memory allocation (code space): 1294
+Frame size for pcre2_match(): 624
+    abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcX\=memory
+malloc  40960
+free unremembered block
+No match
+    abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcX\=find_limits
+Minimum heap limit = 22
+Minimum match limit = 37
+Minimum depth limit = 35
+No match
+
+/ab(cd)/
+Memory allocation (code space): 36
+Frame size for pcre2_match(): 144
+    abcd\=memory
+ 0: abcd
+ 1: cd
+    abcd\=memory,ovector=0 
+free    40960
+free unremembered block
+malloc    128
+malloc  20480
+ 0: abcd
+ 1: cd
diff --git a/testdata/testoutputheap-32 b/testdata/testoutputheap-32
new file mode 100644
index 0000000..36fa1e3
--- /dev/null
+++ b/testdata/testoutputheap-32
@@ -0,0 +1,40 @@
+#pattern framesize, memory
+
+/abcd/
+Memory allocation (code space): 52
+Frame size for pcre2_match(): 128
+    abcd\=memory
+malloc  20480
+ 0: abcd
+    abcd\=find_limits
+Minimum heap limit = 1
+Minimum match limit = 2
+Minimum depth limit = 2
+ 0: abcd
+
+/(((((((((((((((((((((((((((((( (^abc|xyz){1,20}$  ))))))))))))))))))))))))))))))/x
+Memory allocation (code space): 2588
+Frame size for pcre2_match(): 624
+    abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcX\=memory
+malloc  40960
+free unremembered block
+No match
+    abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcX\=find_limits
+Minimum heap limit = 22
+Minimum match limit = 37
+Minimum depth limit = 35
+No match
+
+/ab(cd)/
+Memory allocation (code space): 72
+Frame size for pcre2_match(): 144
+    abcd\=memory
+ 0: abcd
+ 1: cd
+    abcd\=memory,ovector=0 
+free    40960
+free unremembered block
+malloc    128
+malloc  20480
+ 0: abcd
+ 1: cd
diff --git a/testdata/testoutputheap-8 b/testdata/testoutputheap-8
new file mode 100644
index 0000000..05a6b0c
--- /dev/null
+++ b/testdata/testoutputheap-8
@@ -0,0 +1,40 @@
+#pattern framesize, memory
+
+/abcd/
+Memory allocation (code space): 15
+Frame size for pcre2_match(): 128
+    abcd\=memory
+malloc  20480
+ 0: abcd
+    abcd\=find_limits
+Minimum heap limit = 1
+Minimum match limit = 2
+Minimum depth limit = 2
+ 0: abcd
+
+/(((((((((((((((((((((((((((((( (^abc|xyz){1,20}$  ))))))))))))))))))))))))))))))/x
+Memory allocation (code space): 855
+Frame size for pcre2_match(): 624
+    abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcX\=memory
+malloc  40960
+free unremembered block
+No match
+    abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcX\=find_limits
+Minimum heap limit = 22
+Minimum match limit = 37
+Minimum depth limit = 35
+No match
+
+/ab(cd)/
+Memory allocation (code space): 23
+Frame size for pcre2_match(): 144
+    abcd\=memory
+ 0: abcd
+ 1: cd
+    abcd\=memory,ovector=0 
+free    40960
+free unremembered block
+malloc    128
+malloc  20480
+ 0: abcd
+ 1: cd