Message 63540 - Python tracker

The situation was the same on win32 with the VC2005 debug build, some
months ago.
I think this is because of the extra stack checks added with "recent"
versions of Visual Studio, together with the fact that local variables
are not shared when optimizations are disabled.

Can you try to raise the stack size on x64 builds? If 2Mb is enough for
32bit, 4Mb should be good in your case.