Generalized Trace Facility (GTF)

The generalized trace facility (GTF) in z/OS® is a service aid that is part of the MVS™ system product. CICS® issues an MVS GTRACE macro to write trace entries to GTF. GTF must be started with the TRACE=USR option in MVS before you start CICS GTF trace.

GTF stores trace entries in a trace table in MVS main storage, or in up to 16 data sets on tape or disk.

If the storage available to GTF becomes full, the next trace entries go to the start, and overlay the trace entries that were formerly there. For more information about setting up GTF in z/OS, see The Generalized Trace Facility (GTF) in z/OS MVS Diagnosis: Tools and Service Aids.

GTF is most useful when you want to integrate trace entries from a CICS region with those from other CICS regions or other programs. GTF can record trace entries from all supported CICS releases, and it can be used by other programs besides CICS, such as the z/OS Communications Server (for SNA). You can relate CICS trace entries to those from the Communications Server using the task identifier in the trace header. However, because different products might run asynchronously, be cautious about using the sequence of trace entries in the GTF trace data set as evidence when you investigate problems.

To extract and format trace entries from GTF, you use the GTFTRACE subcommand in the interactive problem control system (IPCS). IPCS calls the CICS-supplied formatting routines DFHTG720 and DFHTR720. You can select the trace entries by specifying options on the USR parameter of the GTFTRACE subcommand for IPCS to select the trace entries, or by specifying options on the CICS parameter GTFTRACE subcommand for IPCS to pass to DFHTR720.