Ok, I guess I just needed to update zlib, just not sure how I did it. I ran my script: Stack Overflow. Ran it again, no changes: same. Ran it a third time, no changes: it updated zlib. Now the script seems to run fine. Sorry to bother everyone.
I create a new .ash file and enter one line:
import <zlib.ash>
Now every time I run this script I get a stack overflow error. Specifically:
Stack overflow during ASH script: (zlib.ash, line 54)
I've made sure the script was up to date (checked it out and updated it using Mafia's script...