Hi Divya,
I think you're talking about REXX for an IBM mainframe. If so, I think you've posted to the wrong forum; we're talking about OS/2 and eComstation here, and even if REXX is pretty much the same on different platforms, I doubt anyone here knows about JES or regions.On a second thought, some of us may be working on mainframes, or maybe there's still some IBMer here that may help you; nonetheless, to have more chances, I'd suggest to post on a more on-topic forum.
Hope this helps...
Bye
Cris