diff --git a/include/boost/regex/v4/perl_matcher.hpp b/include/boost/regex/v4/perl_matcher.hpp
index 52e0bcec..190ff84e 100644
--- a/include/boost/regex/v4/perl_matcher.hpp
+++ b/include/boost/regex/v4/perl_matcher.hpp
@@ -366,7 +366,7 @@ public:
       BidiIterator l_base)
       :  m_result(what), base(first), last(end), 
          position(first), backstop(l_base), re(e), traits_inst(e.get_traits()), 
-         m_independent(false), next_count(&rep_obj), rep_obj(&next_count), recursion_stack_position(0)
+         m_independent(false), next_count(&rep_obj), rep_obj(&next_count)/*, recursion_stack_position(0)*/
    {
       construct_init(e, f);
    }
@@ -488,8 +488,8 @@ private:
    // the bitmask to use when determining whether a match_any matches a newline or not:
    unsigned char match_any_mask;
    // recursion information:
-   recursion_info<results_type> recursion_stack[50];
-   unsigned recursion_stack_position;
+   std::vector<recursion_info<results_type> > recursion_stack;
+   //unsigned recursion_stack_position;
 
 #ifdef BOOST_REGEX_NON_RECURSIVE
    //
diff --git a/include/boost/regex/v4/perl_matcher_common.hpp b/include/boost/regex/v4/perl_matcher_common.hpp
index fd439f84..1657d483 100644
--- a/include/boost/regex/v4/perl_matcher_common.hpp
+++ b/include/boost/regex/v4/perl_matcher_common.hpp
@@ -735,7 +735,7 @@ inline bool perl_matcher<BidiIterator, Allocator, traits>::match_assert_backref(
       int id = -index-1;
       if(id >= 10000)
          id = re.get_data().get_id(id);
-      result = recursion_stack_position && ((recursion_stack[recursion_stack_position-1].id == id) || (index == 0));
+      result = !recursion_stack.empty() && ((recursion_stack.back().id == id) || (index == 0));
       pstate = pstate->next.p;
    }
    return result;
diff --git a/include/boost/regex/v4/perl_matcher_non_recursive.hpp b/include/boost/regex/v4/perl_matcher_non_recursive.hpp
index 0fcd4548..a3bc61f8 100644
--- a/include/boost/regex/v4/perl_matcher_non_recursive.hpp
+++ b/include/boost/regex/v4/perl_matcher_non_recursive.hpp
@@ -898,19 +898,20 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_recursion()
    //
    // Set new call stack:
    //
-   if(recursion_stack_position >= static_cast<int>(sizeof(recursion_stack)/sizeof(recursion_stack[0])))
+   if(recursion_stack.capacity() == 0)
    {
-      return false;
+      recursion_stack.reserve(50);
    }
-   recursion_stack[recursion_stack_position].preturn_address = pstate->next.p;
-   recursion_stack[recursion_stack_position].results = *m_presult;
+   recursion_stack.push_back(recursion_info<results_type>());
+   recursion_stack.back().preturn_address = pstate->next.p;
+   recursion_stack.back().results = *m_presult;
    if(static_cast<const re_recurse*>(pstate)->state_id > 0)
    {
       push_repeater_count(static_cast<const re_recurse*>(pstate)->state_id, &next_count);
    }
    pstate = static_cast<const re_jump*>(pstate)->alt.p;
-   recursion_stack[recursion_stack_position].id = static_cast<const re_brace*>(pstate)->index;
-   ++recursion_stack_position;
+   recursion_stack.back().id = static_cast<const re_brace*>(pstate)->index;
+   //++recursion_stack_position;
    //BOOST_ASSERT(recursion_stack[recursion_stack_position-1].id);
 
    return true;
@@ -927,14 +928,15 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_endmark()
       {
          m_presult->set_second(position, index);
       }
-      if(recursion_stack_position)
+      if(!recursion_stack.empty())
       {
-         if(index == recursion_stack[recursion_stack_position-1].id)
+         if(index == recursion_stack.back().id)
          {
-            --recursion_stack_position;
-            pstate = recursion_stack[recursion_stack_position].preturn_address;
-            *m_presult = recursion_stack[recursion_stack_position].results;
-            push_recursion(recursion_stack[recursion_stack_position].id, recursion_stack[recursion_stack_position].preturn_address, &recursion_stack[recursion_stack_position].results);
+            //--recursion_stack_position;
+            pstate = recursion_stack.back().preturn_address;
+            *m_presult = recursion_stack.back().results;
+            push_recursion(recursion_stack.back().id, recursion_stack.back().preturn_address, &recursion_stack.back().results);
+            recursion_stack.pop_back();
          }
       }
    }
@@ -951,13 +953,14 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_endmark()
 template <class BidiIterator, class Allocator, class traits>
 bool perl_matcher<BidiIterator, Allocator, traits>::match_match()
 {
-   if(recursion_stack_position)
+   if(!recursion_stack.empty())
    {
-      BOOST_ASSERT(0 == recursion_stack[recursion_stack_position-1].id);
-      --recursion_stack_position;
-      pstate = recursion_stack[recursion_stack_position].preturn_address;
-      *m_presult = recursion_stack[recursion_stack_position].results;
-      push_recursion(recursion_stack[recursion_stack_position].id, recursion_stack[recursion_stack_position].preturn_address, &recursion_stack[recursion_stack_position].results);
+      BOOST_ASSERT(0 == recursion_stack.back().id);
+      //--recursion_stack_position;
+      pstate = recursion_stack.back().preturn_address;
+      *m_presult = recursion_stack.back().results;
+      push_recursion(recursion_stack.back().id, recursion_stack.back().preturn_address, &recursion_stack.back().results);
+      recursion_stack.pop_back();
       return true;
    }
    if((m_match_flags & match_not_null) && (position == (*m_presult)[0].first))
@@ -1523,10 +1526,11 @@ bool perl_matcher<BidiIterator, Allocator, traits>::unwind_recursion(bool r)
    saved_recursion<results_type>* pmp = static_cast<saved_recursion<results_type>*>(m_backup_state);
    if(!r)
    {
-      recursion_stack[recursion_stack_position].id = pmp->recursion_id;
-      recursion_stack[recursion_stack_position].preturn_address = pmp->preturn_address;
-      recursion_stack[recursion_stack_position].results = pmp->results;
-      ++recursion_stack_position;
+      recursion_stack.push_back(recursion_info<results_type>());
+      recursion_stack.back().id = pmp->recursion_id;
+      recursion_stack.back().preturn_address = pmp->preturn_address;
+      recursion_stack.back().results = pmp->results;
+      //++recursion_stack_position;
    }
    boost::re_detail::inplace_destroy(pmp++);
    m_backup_state = pmp;
@@ -1539,7 +1543,7 @@ bool perl_matcher<BidiIterator, Allocator, traits>::unwind_recursion_pop(bool r)
    saved_state* pmp = static_cast<saved_state*>(m_backup_state);
    if(!r)
    {
-      --recursion_stack_position;
+      recursion_stack.pop_back();
    }
    boost::re_detail::inplace_destroy(pmp++);
    m_backup_state = pmp;
diff --git a/include/boost/regex/v4/perl_matcher_recursive.hpp b/include/boost/regex/v4/perl_matcher_recursive.hpp
index d0de8025..92bb2136 100644
--- a/include/boost/regex/v4/perl_matcher_recursive.hpp
+++ b/include/boost/regex/v4/perl_matcher_recursive.hpp
@@ -857,16 +857,17 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_recursion()
    //
    // Set new call stack:
    //
-   if(recursion_stack_position >= static_cast<int>(sizeof(recursion_stack)/sizeof(recursion_stack[0])))
+   if(recursion_stack.capacity() == 0)
    {
-      return false;
+      recursion_stack.reserve(50);
    }
-   recursion_stack[recursion_stack_position].preturn_address = pstate->next.p;
-   recursion_stack[recursion_stack_position].results = *m_presult;
-   recursion_stack[recursion_stack_position].repeater_stack = next_count;
+   recursion_stack.push_back(recursion_info<results_type>());
+   recursion_stack.back().preturn_address = pstate->next.p;
+   recursion_stack.back().results = *m_presult;
+   recursion_stack.back().repeater_stack = next_count;
    pstate = static_cast<const re_jump*>(pstate)->alt.p;
-   recursion_stack[recursion_stack_position].id = static_cast<const re_brace*>(pstate)->index;
-   ++recursion_stack_position;
+   recursion_stack.back().id = static_cast<const re_brace*>(pstate)->index;
+   //++recursion_stack_position;
 
    repeater_count<BidiIterator>* saved = next_count;
    repeater_count<BidiIterator> r(&next_count); // resets all repeat counts since we're recursing and starting fresh on those
@@ -876,9 +877,10 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_recursion()
 
    if(!result)
    {
-      --recursion_stack_position;
-      next_count = recursion_stack[recursion_stack_position].repeater_stack;
-      *m_presult = recursion_stack[recursion_stack_position].results;
+      //--recursion_stack_position;
+      next_count = recursion_stack.back().repeater_stack;
+      *m_presult = recursion_stack.back().results;
+      recursion_stack.pop_back();
       return false;
    }
    return true;
@@ -895,20 +897,21 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_endmark()
       {
          m_presult->set_second(position, index);
       }
-      if(recursion_stack_position)
+      if(!recursion_stack.empty())
       {
-         if(index == recursion_stack[recursion_stack_position-1].id)
+         if(index == recursion_stack.back().id)
          {
-            --recursion_stack_position;
-            recursion_info<results_type> saved = recursion_stack[recursion_stack_position];
+            //--recursion_stack_position;
+            recursion_info<results_type> saved = recursion_stack.back();
+            recursion_stack.pop_back();
             const re_syntax_base* saved_state = pstate = saved.preturn_address;
             repeater_count<BidiIterator>* saved_count = next_count;
             next_count = saved.repeater_stack;
             *m_presult = saved.results;
             if(!match_all_states())
             {
-               recursion_stack[recursion_stack_position] = saved;
-               ++recursion_stack_position;
+               recursion_stack.push_back(saved);
+               //++recursion_stack_position;
                next_count = saved_count;
                return false;
             }
@@ -928,17 +931,19 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_endmark()
 template <class BidiIterator, class Allocator, class traits>
 bool perl_matcher<BidiIterator, Allocator, traits>::match_match()
 {
-   if(recursion_stack_position)
+   if(!recursion_stack.empty())
    {
-      BOOST_ASSERT(0 == recursion_stack[recursion_stack_position-1].id);
-      --recursion_stack_position;
-      const re_syntax_base* saved_state = pstate = recursion_stack[recursion_stack_position].preturn_address;
-      *m_presult = recursion_stack[recursion_stack_position].results;
+      BOOST_ASSERT(0 == recursion_stack.back().id);
+      //--recursion_stack_position;
+      const re_syntax_base* saved_state = pstate = recursion_stack.back().preturn_address;
+      *m_presult = recursion_stack.back().results;
+      recursion_stack.pop_back();
       if(!match_all_states())
       {
-         recursion_stack[recursion_stack_position].preturn_address = saved_state;
-         recursion_stack[recursion_stack_position].results = *m_presult;
-         ++recursion_stack_position;
+         recursion_stack.push_back(recursion_info<results_type>());
+         recursion_stack.back().preturn_address = saved_state;
+         recursion_stack.back().results = *m_presult;
+         //++recursion_stack_position;
          return false;
       }
       return true;
diff --git a/performance/command_line.cpp b/performance/command_line.cpp
index 114dceba..7c7a5a68 100644
--- a/performance/command_line.cpp
+++ b/performance/command_line.cpp
@@ -100,6 +100,9 @@ int handle_argument(const std::string& what)
 #endif
 #ifdef BOOST_HAS_PCRE
       time_pcre = true;
+#endif
+#ifdef BOOST_HAS_XPRESSIVE
+      time_xpressive = true;
 #endif
    }
    else if(what == "-test-matches")