z/OS Communications Server exit tracing

z/OS® Communications Server SNA exit tracing gives you a way of tracing SNA requests made from CICS®.

You can control it online, using transaction CETR. See Figure 1 for an illustration of the screen you need to use.

When CICS issues an SNA request, SNA services the request asynchronously and CICS continues executing. When SNA has finished with the request, it returns control to CICS by driving a CICS SNA exit. Every such exit contains a trace point, and if CICS SNA exit tracing is active, a trace entry is written to the GTF trace data set. GTF tracing must be active, but you do not need to start it explicitly from CICS. It is enough to start SNA exit tracing from the CETR transaction and terminal trace panel.

Note: The GTF trace data set can receive trace entries from a variety of jobs running in different address spaces. You need to identify the trace entries that have been made from the CICS region that interests you. You can do this by looking at the job name that precedes every trace entry in the formatted output.

You can use this type of tracing in any of the cases where you might want to use SNA buffer tracing, but it has the advantage of being part of CICS and, therefore, controllable from CICS. This means that you do not need a good understanding of SNA system programming to be able to use it. CICS SNA exit tracing also has the advantage of tracing some important CICS data areas relating to SNA requests, which might be useful for diagnosing problems.