diff -up openjdk/hotspot/src/os_cpu/linux_zero/vm/globals_linux_zero.hpp.ppc64 openjdk/hotspot/src/os_cpu/linux_zero/vm/globals_linux_zero.hpp
--- openjdk/hotspot/src/os_cpu/linux_zero/vm/globals_linux_zero.hpp.ppc64	2013-02-22 19:02:06.000000000 +0100
+++ openjdk/hotspot/src/os_cpu/linux_zero/vm/globals_linux_zero.hpp	2013-04-18 16:21:24.897403406 +0200
@@ -32,11 +32,15 @@
 //
 
 define_pd_global(bool,  DontYieldALot,           false);
-define_pd_global(intx,  ThreadStackSize,         1536);
+define_pd_global(intx,  ThreadStackSize,         1664);
 #ifdef _LP64
-define_pd_global(intx,  VMThreadStackSize,       1024);
+#if defined (_LITTLE_ENDIAN) && defined (__powerpc64__)
+define_pd_global(intx,  VMThreadStackSize,       1920);
 #else
-define_pd_global(intx,  VMThreadStackSize,       512);
+define_pd_global(intx,  VMThreadStackSize,       1280);
+#endif
+#else
+define_pd_global(intx,  VMThreadStackSize,       640);
 #endif // _LP64
 define_pd_global(intx,  CompilerThreadStackSize, 0);
 define_pd_global(uintx, JVMInvokeMethodSlack,    8192);