diff --git a/harbour/ChangeLog b/harbour/ChangeLog
index c65a69e9a4..3f7bf52a0e 100644
--- a/harbour/ChangeLog
+++ b/harbour/ChangeLog
@@ -17,6 +17,28 @@
    past entries belonging to author(s): Viktor Szakats.
 */
 
+2009-11-24 16:48 UTC+0100 Przemyslaw Czerpak (druzus/at/priv.onet.pl)
+  * harbour/src/vm/dlmalloc.c
+    % use harbour spin locks if available by default in all builds
+
+  * harbour/include/hbatomic.h
+    * removed HB_SPINLOCK_SLEEP macro and enable code to always yield
+      the processor in spin locks
+    * cover double spin lock setting by HB_SPINLOCK_REPEAT
+
+  * harbour/src/vm/garbage.c
+    * removed unused HB_SPINLOCK_SLEEP macro
+
+  * harbour/include/hbstack.h
+  * harbour/src/vm/estack.c
+    + added new internal function hb_stackAllocator()
+    * disable hb_stackTotalItems() stack macro so this function can be
+      used also in internal HVM code to check if stack is initialized
+
+  * harbour/src/vm/fm.c
+    ! use hb_stackAllocator() to access pointer to DLMALLOC mspace
+      It should fix GPF when DLMT was used in OS2 builds - please test.
+
 2009-11-24 07:43 UTC-0800 Pritpal Bedi (pritpal@vouchcac.com)
   * contrib/hbxbp/xbplistbox.prg
   * contrib/hbxbp/xbptreeview.prg
diff --git a/harbour/include/hbatomic.h b/harbour/include/hbatomic.h
index f1e80e57c5..9c49924f65 100644
--- a/harbour/include/hbatomic.h
+++ b/harbour/include/hbatomic.h
@@ -72,6 +72,22 @@
 
 HB_EXTERN_BEGIN
 
+/* yield the processor */
+#if defined( HB_TASK_THREAD )
+#  define HB_SCHED_YIELD()    hb_taskYield()
+#elif defined( HB_OS_WIN )
+#  define HB_SCHED_YIELD()    Sleep( 0 )
+#elif defined( HB_OS_OS2 )
+#  define HB_SCHED_YIELD()    DosSleep( 0 )
+#elif defined( __SVR4 )
+#  define HB_SCHED_YIELD()    thr_yield()
+#elif defined( HB_OS_UNIX )
+#  define HB_SCHED_YIELD()    sched_yield()
+#else
+#  define HB_SCHED_YIELD()    sleep( 0 );
+#endif
+
+
 /* Inline assembler version of atomic operations on memory reference counters */
 #if defined( __GNUC__ )
 
@@ -150,23 +166,11 @@ HB_EXTERN_BEGIN
             if( !hb_spinlock_trylock( l ) )
                return;
 
-            #ifdef HB_SPINLOCK_SLEEP
+            #ifdef HB_SPINLOCK_REPEAT
                if( !hb_spinlock_trylock( l ) )
                   return;
-               #if defined( HB_TASK_THREAD )
-                  hb_taskYield();
-               #elif defined( HB_OS_WIN )
-                  Sleep( 0 );
-               #elif defined( HB_OS_OS2 )
-                  DosSleep( 0 );
-               #elif defined( __SVR4 )
-                  thr_yield();
-               #elif defined( HB_OS_UNIX )
-                  sched_yield();
-               #else
-                  sleep( 0 );
-               #endif
             #endif
+            HB_SCHED_YIELD();
          }
       }
 
@@ -195,23 +199,11 @@ HB_EXTERN_BEGIN
             if( !__sync_lock_test_and_set( l, 1 ) )
                return;
 
-            #ifdef HB_SPINLOCK_SLEEP
+            #ifdef HB_SPINLOCK_REPEAT
                if( !__sync_lock_test_and_set( l, 1 ) )
                   return;
-               #if defined( HB_TASK_THREAD )
-                  hb_taskYield();
-               #elif defined( HB_OS_WIN )
-                  Sleep( 0 );
-               #elif defined( HB_OS_OS2 )
-                  DosSleep( 0 );
-               #elif defined( __SVR4 )
-                  thr_yield();
-               #elif defined( HB_OS_UNIX )
-                  sched_yield();
-               #else
-                  sleep( 0 );
-               #endif
             #endif
+            HB_SCHED_YIELD();
          }
       }
 
@@ -356,23 +348,11 @@ HB_EXTERN_BEGIN
             if( !hb_spinlock_trylock( l ) )
                return;
 
-            #ifdef HB_SPINLOCK_SLEEP
+            #ifdef HB_SPINLOCK_REPEAT
                if( !hb_spinlock_trylock( l ) )
                   return;
-               #if defined( HB_TASK_THREAD )
-                  hb_taskYield();
-               #elif defined( HB_OS_WIN )
-                  Sleep( 0 );
-               #elif defined( HB_OS_OS2 )
-                  DosSleep( 0 );
-               #elif defined( __SVR4 )
-                  thr_yield();
-               #elif defined( HB_OS_UNIX )
-                  sched_yield();
-               #else
-                  sleep( 0 );
-               #endif
             #endif
+            HB_SCHED_YIELD();
          }
       }
 
@@ -416,16 +396,21 @@ HB_EXTERN_BEGIN
 #  if !defined( HB_SPINLOCK_T )
 #     define HB_SPINLOCK_T          volatile LONG
 #     define HB_SPINLOCK_INIT       0
-#     define HB_SPINLOCK_ACQUIRE(l) do { \
-                                       for( ;; ) \
-                                       { \
+#     ifdef HB_SPINLOCK_REPEAT
+#        define HB_SPINLOCK_ACQUIRE(l) do { \
                                           if( !InterlockedExchange( (LONG*)(l), 1 ) ) \
                                              break; \
                                           if( !InterlockedExchange( (LONG*)(l), 1 ) ) \
                                              break; \
                                           Sleep( 0 ); \
-                                       } \
-                                    } while(0)
+                                       } while(1)
+#     else
+#        define HB_SPINLOCK_ACQUIRE(l) do { \
+                                          if( !InterlockedExchange( (LONG*)(l), 1 ) ) \
+                                             break; \
+                                          Sleep( 0 ); \
+                                       } while(1)
+#     endif
 #     define HB_SPINLOCK_RELEASE(l) do { *(l) = 0; } while(0)
 #  endif
 
@@ -480,16 +465,21 @@ HB_EXTERN_BEGIN
 #  if !defined( HB_SPINLOCK_T )
 #     define HB_SPINLOCK_T          volatile uint_t
 #     define HB_SPINLOCK_INIT       0
-#     define HB_SPINLOCK_ACQUIRE(l) do { \
-                                       for( ;; ) \
-                                       { \
+#     ifdef HB_SPINLOCK_REPEAT
+#        define HB_SPINLOCK_ACQUIRE(l) do { \
                                           if( !atomic_swap_uint( (l), 1 ) ) \
                                              break; \
                                           if( !atomic_swap_uint( (l), 1 ) ) \
                                              break; \
                                           thr_yield(); \
-                                       } \
-                                    } while(0)
+                                       } while(1)
+#     else
+#        define HB_SPINLOCK_ACQUIRE(l) do { \
+                                          if( !atomic_swap_uint( (l), 1 ) ) \
+                                             break; \
+                                          thr_yield(); \
+                                       } while(1)
+#     endif
 #     define HB_SPINLOCK_RELEASE(l) do { *(l) = 0; } while(0)
 #  endif
 
diff --git a/harbour/include/hbstack.h b/harbour/include/hbstack.h
index a308b19992..7a969070e0 100644
--- a/harbour/include/hbstack.h
+++ b/harbour/include/hbstack.h
@@ -357,6 +357,7 @@ extern void        hb_stackIsStackRef( void *, PHB_TSD_FUNC );
    extern void             hb_stackSetQuitState( USHORT uiState );
    extern int              hb_stackUnlock( void );
    extern int              hb_stackLock( void );
+   extern void *           hb_stackAllocator( void );
 #endif
 
 #endif /* _HB_API_INTERNAL_ */
@@ -372,7 +373,7 @@ extern void        hb_stackIsStackRef( void *, PHB_TSD_FUNC );
 #define hb_stackItemFromBase( n )   ( * ( hb_stack.pBase + ( int ) ( n ) + 1 ) )
 #define hb_stackTopOffset( )        ( hb_stack.pPos - hb_stack.pItems )
 #define hb_stackBaseOffset( )       ( hb_stack.pBase - hb_stack.pItems + 1 )
-#define hb_stackTotalItems( )       ( hb_stack.wItems )
+/* #define hb_stackTotalItems( )       ( hb_stack.wItems ) */
 #define hb_stackBaseItem( )         ( * hb_stack.pBase )
 #define hb_stackSelfItem( )         ( * ( hb_stack.pBase + 1 ) )
 #define hb_stackItem( iItemPos )    ( * ( hb_stack.pItems + ( long ) ( iItemPos ) ) )
diff --git a/harbour/src/vm/dlmalloc.c b/harbour/src/vm/dlmalloc.c
index b3449574e9..7774cd1afd 100644
--- a/harbour/src/vm/dlmalloc.c
+++ b/harbour/src/vm/dlmalloc.c
@@ -1449,20 +1449,20 @@ static int win32munmap(void* ptr, size_t size) {
     unique mparams values are initialized only once.
 */
 
-#if defined( HB_OS_OS2 ) || defined( HB_OS_WIN ) || defined( __WATCOMC__ )
+#ifdef HB_MT_VM
 #  ifndef HB_SPINLOCK_USE
 #     define HB_SPINLOCK_USE
-#  endif
-#endif
+#  endif  /* HB_SPINLOCK_USE */
+#endif  /* HB_MT_VM */
 
 #ifdef HB_SPINLOCK_USE
 #  include "hbthread.h"
 #  include "hbatomic.h"
-#endif
+#endif  /* HB_SPINLOCK_USE */
 
 #ifndef HB_SPINLOCK_T
 #  undef HB_SPINLOCK_USE
-#endif
+#endif  /* HB_SPINLOCK_T */
 
 #ifdef HB_SPINLOCK_USE
 
diff --git a/harbour/src/vm/estack.c b/harbour/src/vm/estack.c
index 4133292f05..73f96b0558 100644
--- a/harbour/src/vm/estack.c
+++ b/harbour/src/vm/estack.c
@@ -835,6 +835,19 @@ LONG hb_stackTotalItems( void )
 #endif
 }
 
+#if defined( HB_MT_VM )
+void * hb_stackAllocator( void )
+{
+   if( hb_stack_ready() )
+   {
+      HB_STACK_TLS_PRELOAD
+
+      return hb_stack.allocator;
+   }
+   return NULL;
+}
+#endif
+
 #undef hb_stackDateBuffer
 char * hb_stackDateBuffer( void )
 {
diff --git a/harbour/src/vm/fm.c b/harbour/src/vm/fm.c
index f4674793f2..a4d81a5a8e 100644
--- a/harbour/src/vm/fm.c
+++ b/harbour/src/vm/fm.c
@@ -381,10 +381,10 @@ static HB_MSPACE s_mspool[ HB_MSPACE_COUNT ];
 
 static mspace hb_mspace( void )
 {
-   HB_STACK_TLS_PRELOAD
+   PHB_MSPACE pm = ( PHB_MSPACE ) hb_stackAllocator();
 
-   if( hb_stackId() && hb_stack.allocator )
-      return ( ( PHB_MSPACE ) hb_stack.allocator )->ms;
+   if( pm )
+      return pm->ms;
 
    if( !s_gm )
       s_gm = create_mspace( 0, 1 );
diff --git a/harbour/src/vm/garbage.c b/harbour/src/vm/garbage.c
index 622784fa8c..7a3381a4e1 100644
--- a/harbour/src/vm/garbage.c
+++ b/harbour/src/vm/garbage.c
@@ -68,8 +68,6 @@
 
 #if defined( HB_MT_VM )
 
-#  define HB_SPINLOCK_SLEEP
-
 #  include "hbthread.h"
 #  include "hbatomic.h"