A global variable wouldn't be elegant, but it would be fast.

HEY! Before you hit that vote button, hear me out...

When factoring recursion out of a routine you MUST use global variables. I've been in those situations where I needed to get rid of recursion because the depth was so great, it was killing performance. Recursion is elegant, but it sucks on performance. Globals are bad in general, but all languages have them, and have them for a reason. Somtimes it's OK to break the rules.

OK, I've said my peace - now you can vote.