Date:         Mon, 27 Feb 2006 16:48:52 -0500
Reply-To:     CICS List <CICS-L@LISTSERV.UGA.EDU>
Sender:       CICS List <CICS-L@LISTSERV.UGA.EDU>
From:         "Masters, Paul1" <paul1.masters@CITIGROUP.COM>
Subject:      Re: Migration running two versions
Content-Type: text/plain; charset="iso-8859-1"

Your concerns are valid.  After all regions are running on the new version of CICS (and you are fairly sure you won't be going back), then you can change the compile process to use the new CICS libraries.

While existing functions should be OK if using the newer version, sometimes internal things change.  While CICS says it is downward compatible (that is older code runs in new versions), it has never been upward compatible (that is new code running in older versions).  Also, someone might use a new feature which would cause an abend (or be unpredictable - or worse).

Of course, any of your 'system' level programs and exits etc. should always be recompiled with the new version libraries.  (Exits should -always- be recompiled.)

What you are doing is standard.  Update LPA/LINKLIST to newest version.  Update regions as applications allows, starting with TEST.  Then, moving on to QA and PROD after applications (hopefully!) has done some testing.

I always create new files for the regions (keep all the systems stuff separate by version).  That way I can go back to the old version if needed simply by renaming the region start JCL.  (It also makes cleanup easier too!  Just delete the files with the old version number in them.)

Hope this helps.

Paul Masters
CTI North America
Southwest Data Center
CICS Support
817-317-8229
paul1.masters@citigroup.com

"Being truthful, when you know it will cost you, is the true test of honesty."
        - Dave Weinbaum



-----Original Message-----
From: CICS List [mailto:CICS-L@LISTSERV.UGA.EDU]On Behalf Of Peggy
Andrews
Sent: Monday, February 27, 2006 03:17 PM
To: CICS-L@LISTSERV.UGA.EDU
Subject: Migration running two versions


Hi, all.

Please bear with me, but this is my first CICS installation and will be my
first time to deal with a migration strategy dealing with running a new
version of CICS in a "test" region, with an older version of CICS running
in its "production" region, both on the same LPAR.

I have successfully installed CICS on our TEST LPAR, and have placed the
new CICS version in LPA and LNKLST.  From there, I know I can successfully
bring up two regions at different levels - got that.  BUT, my question now
has to do with the applications staff on the our PROD LPAR.  They would
like me to bring up their "test" region at the new level.  They would then
proceed to test there while going about business as usual.  They may do
compiles there, I don't know.  Anyway, if they do and that module is
compiled with the new level libraries, what happens if they need to move it
to the "production" region, at the lower level?  Is my only concern that
they recompile it with the production's lower level?

I'm sure many of you have had to follow some sort of strategy/backout in
this scenario, and am looking forward to your experienced suggestions.

Thanks much!
Peggy