Lowering RUBY_STACK_MIN_LIMIT to 64KB across the board in
thread_pthread.c seems to work fine for check, test-rubyspec,
benchmark-each.

No real code, though, and I also don't know what outside C extensions
do, but 64KB is the PTHREAD_STACK_MIN for my platform (and I've always
felt it was too high).

diff --git a/thread_pthread.c b/thread_pthread.c
index ad6f716..a015873 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -630,11 +630,7 @@ use_cached_thread(rb_thread_t *th)
 }
 
 enum {
-#ifdef __SYMBIAN32__
-    RUBY_STACK_MIN_LIMIT = 64 * 1024,  /* 64KB: Let's be slightly more frugal on mobile platform */
-#else
-    RUBY_STACK_MIN_LIMIT = 512 * 1024, /* 512KB */
-#endif
+    RUBY_STACK_MIN_LIMIT = 64 * 1024,  /* 64KB */
     RUBY_STACK_SPACE_LIMIT = 1024 * 1024
 };
 
-- 
Eric Wong