diff --git a/Python/thread_os2.h b/Python/thread_os2.h
index eeefe03..a18ce6f 100644
--- a/Python/thread_os2.h
+++ b/Python/thread_os2.h
@@ -14,6 +14,10 @@
 long PyThread_get_thread_ident(void);
 #endif
 
+#if !defined(THREAD_STACK_SIZE)
+#define	THREAD_STACK_SIZE	0x10000
+#endif
+
 /*
  * Initialization of the C package, should not be needed.
  */
@@ -31,7 +35,7 @@
 	int aThread;
 	int success = 0;
 
-	aThread = _beginthread(func,NULL,65536,arg);
+	aThread = _beginthread(func, NULL, THREAD_STACK_SIZE, arg);
 
 	if (aThread == -1) {
 		success = -1;