This series is intended to help new CICS support people understand the basics of the product and how it has evolved. It covers basic concepts, underlying components that may not be intuitively obvious and daily support issues. For more information about this article series and a list of what readers should already know, see the first article at
http://esmpubs.com/q1hhi. To read the previous article in this series, go to http://esmpubs.com/1egx0.
Since CICS went Object Code Only (OCO), IBM has been forthcoming with documenting changes and upgrades to the product. One of the areas where IBM has provided information is the trace domain that’s used to document the program flow during execution. This additional documentation is critical, since every new release contains enhancements that may change the way customers deal with problem diagnosis. For this reason, every debugging utility (especially trace and dump) is shipped with the release in the program name.
Trace entries are extremely helpful in diagnosing any problem. The trace provides you with the command flow of the program and identifies any exceptional situations that have occurred during the execution of the transaction. Let’s take a look at how we can format trace entries. Note that we will use CICS Transaction Server Version 4.1 as our example here, but the process of using trace for problem determination is similar in all releases.
Now, for example, if you want to format trace entries in this release, you would expect the program name to be DFHTU410, but that isn’t the case. There’s a difference in the naming convention between CICS release and CICS level. If you’re unsure which name to use for the specific release you’re running, use the Master Terminal transaction CEMT as follows.
If you’re logged into any region, you can use the INQuire SYStem command and it will return a number of values, including the following:
CEMT INQ SYS output
As you can see, while the CICSTSLEVEL shows 4.1, the RELEASE value is 660. IBM uses the two values for different purposes, including program names for some of the utilities. So, when formatting trace entries for CICS TS V4.1, you would use program name DFHTU660. More about this later.
CICS-Supplied Transactions: CETR
This transaction, which is shipped with every new release, can be affected by enhancements to the product; for example, new domains. All the options in CETR allow customers to turn on or suppress any domain or facility and the corresponding trace entries. This allows customization and selectivity in what’s written to the trace data set.
The CETR transaction initially brings up the main menu with global options. The Internal Status should be STARTED to write trace entries to the internal trace table.
The trace table size is specified here, and the default is 16K, which is much too small. The entries are written “above the line” so storage isn’t an issue; most customers specify a minimum size of 5 MB.