Some years ago, we force the default minimum stack size for JVM threads to 2048k, because the default (on 64-bit) of 1024k was too small for some recursion-heavy tools like Bundler. We blew out that stack a lot also because our AST was a recursive interpreter. Since then, bundler has been made iterative and we now interpret a flat structure...so it may be possible for us to drop our stack size tweaking too.

Relates to #3739.