diff --git a/reactos/ntoskrnl/include/internal/ps.h b/reactos/ntoskrnl/include/internal/ps.h
index be0efad0853..6d209e74248 100644
--- a/reactos/ntoskrnl/include/internal/ps.h
+++ b/reactos/ntoskrnl/include/internal/ps.h
@@ -16,7 +16,7 @@
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
-/* $Id: ps.h,v 1.50 2003/07/17 16:57:38 silverblade Exp $
+/* $Id: ps.h,v 1.51 2003/07/23 19:13:37 dwelch Exp $
  *
  * FILE:            ntoskrnl/ke/kthread.c
  * PURPOSE:         Process manager definitions
@@ -540,6 +540,9 @@ PsTerminateWin32Process (PEPROCESS Process);
 VOID
 PsTerminateWin32Thread (PETHREAD Thread);
 
+VOID
+PsInitialiseW32Call(VOID);
+
 #endif /* ASSEMBLER */
 
 #endif /* __INCLUDE_INTERNAL_PS_H */
diff --git a/reactos/ntoskrnl/ps/psmgr.c b/reactos/ntoskrnl/ps/psmgr.c
index cf1e3c73495..0a503f72a61 100644
--- a/reactos/ntoskrnl/ps/psmgr.c
+++ b/reactos/ntoskrnl/ps/psmgr.c
@@ -1,4 +1,4 @@
-/* $Id: psmgr.c,v 1.15 2003/07/11 01:23:15 royce Exp $
+/* $Id: psmgr.c,v 1.16 2003/07/23 19:13:37 dwelch Exp $
  *
  * COPYRIGHT:               See COPYING in the top level directory
  * PROJECT:                 ReactOS kernel
@@ -33,6 +33,7 @@ VOID PiInitProcessManager(VOID)
    PsInitIdleThread();
    PiInitApcManagement();
    PsInitialiseSuspendImplementation();
+   PsInitialiseW32Call();
 }
 
 
diff --git a/reactos/ntoskrnl/ps/w32call.c b/reactos/ntoskrnl/ps/w32call.c
index 630e6d67f5c..6e5e98703d5 100644
--- a/reactos/ntoskrnl/ps/w32call.c
+++ b/reactos/ntoskrnl/ps/w32call.c
@@ -1,4 +1,4 @@
-/* $Id: w32call.c,v 1.7 2003/07/21 21:53:53 royce Exp $
+/* $Id: w32call.c,v 1.8 2003/07/23 19:13:37 dwelch Exp $
  *
  * COPYRIGHT:              See COPYING in the top level directory
  * PROJECT:                ReactOS kernel
@@ -46,8 +46,22 @@ typedef struct _NTW32CALL_SAVED_STATE
   PVOID SavedCallbackStack;
 } NTW32CALL_SAVED_STATE, *PNTW32CALL_SAVED_STATE;
 
+typedef struct
+{
+  PVOID BaseAddress;
+  LIST_ENTRY ListEntry;
+} NTW32CALL_CALLBACK_STACK, *PNTW32CALL_CALLBACK_STACK;
+
+static LIST_ENTRY CallbackStackListHead;
+
 /* FUNCTIONS ***************************************************************/
 
+VOID
+PsInitialiseW32Call(VOID)
+{
+  InitializeListHead(&CallbackStackListHead);
+}
+
 NTSTATUS STDCALL
 NtCallbackReturn (PVOID		Result,
 		  ULONG		ResultLength,
@@ -145,6 +159,22 @@ PsFreeCallbackStack(PVOID StackLimit)
   MmUnlockAddressSpace(MmGetKernelAddressSpace());
 }
 
+VOID
+PsFreeCallbackStacks(VOID)
+{
+  PLIST_ENTRY CurrentListEntry;
+  PNTW32CALL_CALLBACK_STACK Current;
+
+  while (!IsListEmpty(&CallbackStackListHead))
+    {
+      CurrentListEntry = RemoveHeadList(&CallbackStackListHead);
+      Current = CONTAINING_RECORD(CurrentListEntry, NTW32CALL_CALLBACK_STACK,
+				  ListEntry);
+      PsFreeCallbackStack(Current->BaseAddress);
+      ExFreePool(Current);
+    }
+}
+
 PVOID STATIC
 PsAllocateCallbackStack(ULONG StackSize)
 {
@@ -202,6 +232,7 @@ NtW32Call (IN ULONG RoutineIndex,
   KIRQL oldIrql;
   NTSTATUS CallbackStatus;
   NTW32CALL_SAVED_STATE SavedState;
+  PNTW32CALL_CALLBACK_STACK AssignedStack;
 
   DPRINT("NtW32Call(RoutineIndex %d, Argument %X, ArgumentLength %d)\n",
 	  RoutineIndex, Argument, ArgumentLength);
@@ -210,7 +241,22 @@ NtW32Call (IN ULONG RoutineIndex,
 
   /* Set up the new kernel and user environment. */
   StackSize = (ULONG)(Thread->Tcb.StackBase - Thread->Tcb.StackLimit);  
-  NewStack = PsAllocateCallbackStack(StackSize);
+  if (IsListEmpty(&CallbackStackListHead))
+    {
+      NewStack = PsAllocateCallbackStack(StackSize);
+      AssignedStack = ExAllocatePool(NonPagedPool,
+				     sizeof(NTW32CALL_CALLBACK_STACK));
+      AssignedStack->BaseAddress = NewStack;
+    }
+  else
+    {
+      PLIST_ENTRY StackEntry;      
+
+      StackEntry = RemoveHeadList(&CallbackStackListHead);
+      AssignedStack = CONTAINING_RECORD(StackEntry, NTW32CALL_CALLBACK_STACK, 
+					ListEntry);
+      NewStack = AssignedStack->BaseAddress;
+    }
   /* FIXME: Need to check whether we were interrupted from v86 mode. */
   memcpy(NewStack + StackSize - sizeof(KTRAP_FRAME), Thread->Tcb.TrapFrame,
 	 sizeof(KTRAP_FRAME) - (4 * sizeof(DWORD)));
@@ -245,7 +291,7 @@ NtW32Call (IN ULONG RoutineIndex,
    * modified.
    */
   KeLowerIrql(PASSIVE_LEVEL);
-  PsFreeCallbackStack(NewStack);
+  InsertTailList(&CallbackStackListHead, &AssignedStack->ListEntry);
   return(CallbackStatus);
 }