Wow: I was just reminded that CICS is now 40 years old, thanks to an article at http://www.eweekeurope.co.uk/news/ibm-touts-cics-relevance-40-years-on-1475 which mentions that it was first released on July 8, 1969 - just on time for the first steps on the moon.
Being relatively young for a mainframer, back then I was barely old enough to grasp what was going on as everyone sat glued to their TVs. And I certainly had no idea about CICS.
That changed in June of 1987 when I went from being a PC-AT C programmer to becoming a brand new mainframer and CICS Systems Programmer. I had to translate all of my understanding from ASCII and keyboard macros and graphical interfaces to EBCDIC and 3270 BMS and CICS. And the tables - oh, the tables: everything about CICS was tables, and still mostly assembled using macros back then.
Not to mention that everything began with "DFH" whether it was macros, load modules or message IDs. They tell me it stands for "Don't Forget Hursley" which is still in many ways the home of CICS. (For more about this, and how to pronounce "CICS," see my blog entry of November 24, 2008 about How to Talk Like a Mainframer.)
As my career progressed, all those tables started to go online using RDO (Resource Definition Online) or become superseded - especially in the case of the DFHSNT, or SigNonTable, which was effectively replaced by external security.
Still, before all that happened, one of my favorite techie memories is changing someone's password in a running production region. For various reasons, we weren't able to wait for the next restart, which occurred nightly; in fact, we had to do it immediately. So, I used what I knew about CICS control blocks and tracked down the DFHSNT in memory, then used my recently-acquired knowledge of EBCDIC to modify the password using a hexadecimal replace command. It was a small and very nerdy thing to do, but to this day I still remember the feeling of victory at having been able to do it so quickly and exactly.
Of course, being a new mainframer, I also made my mistakes, including accidentally causing a restart of a critical production CICS region right in the middle of the day. I reloaded a buffer pool module that had all kinds of active pointers in it, and CICS immediately cratered. Believe me, I didn't do that twice.
Today, I still have a nerdy affection for CICS, my first mainframe focus and still a great system. In fact, I even have a light blue CICS golf shirt from SHARE, and I look forward to singing, "These are a few of my favorite CICS!" at the JES2 sing-along Thursday evening every SHARE.
So, happy XL, CICS: may you continue to XL well beyond C!