After upgrading to BSA 8.9.00.136 (Windows 2008 application servers) we started seeing "nsh:13: fork failed" on all our NSH script job. More than half of the targets were failing when the script was ran. I found other discussions on this same topic but for much older version of BSA. I opened to trouble ticket and was then directed to the following fix:
After applying the fix to all our app servers the problem of "nsh:13: fork failed" is now gone.