The Master Terminal

Everyone has things in their lives that annoy them but instead of working on a solution, they just live with it because they either haven’t thought about it or the workaround is quick enough that it doesn’t really matter that much.

Since I started in CICS almost 5 years ago (has it been that long already!) I’ve always just accepted that if I’d forgotten to activate my VTAM applids before I brought a CICS region up, the quickest course of action was just to activate my applids and restart CICS. Now, I had always just assumed that there was a better way of doing that but there was always something else more important to worry about. So, no idea what we were discussing at the time, but somehow Grant managed to slip the solution to this one into our conversation. Now I am sure this is just the most obvious thing in the world to most of our readers but I thought I’d share the solution anyway.

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Every now and then you come across a problem that you just can’t fix with the tools in your toolbelt. The problem? How to detect what part of your program is changing a specific area of storage? The program in question being CICSPlex SM and the storage a 1 byte flag stored in a MVS dataspace. A code search only proved that the flag was not being modified anywhere obvious and a trace of the suspect modules proved unhelpful.

So failing to batter the problem into submission with the normal tools, a kind colleague pointed me at the MVS SLIP (Serviceability Level Indication Processing) operator command. A few painful moments passed as the correct command incantation was established and lo and behold I received a dump with the PSW pointing handily at the module that changed the storage location. Thankfully we use eye-catchers at the top of each internal method so detecting the module is simply a matter of browsing the dump at the address suggested and scrolling up.

Generally within the CICS TS team the most commonly used tools for debugging problems are CEMT, CECI, IPCS, AUX trace and an internal interactive debugging tool called Source Language Debug (SLD). In CICSPlex SM development/service we also use the customer-provided COD0 transaction to quickly walk-around the system control blocks and dump out specific data.

The SLIP command is definitely one tool I’ll be adding to my toolbelt. What tools can you not live without?