>> I don't know if he has a version that you could use in z/OS or TSO.
No - I don't, but a good friend of mine Chuck Arney has a Debugger that was written based on the same technique to intercept execution.
Here is a copy from the website at: http://arneycomputer.com/<http://www.zosdebug.com> Trap Diagnostic Facility is an innovative z/OS assembler debugging facility
Martin
