GTF tracing of Input/Output buffers

If MVS/APPC is running and the LU is not defined as LU=OWN, VTAM® traces the input/ output buffers to see what is being exchanged between the source and target servers. GTF trace, an MVS facility, is used by VTAM to collect trace records. The VTAM trace can show buffer contents. VTAM trace can also show SNA request and response information. The following information shows VTAM commands and functions:

Turn on the GTF trace facility:
S GTF.IT
R xx, TRACE=RNIO,USR
R xx U

When the GTF initialization is complete, GTF tells you the name of the trace data set in message AHL906I.

Find the VTAM LU to trace:
D APPC,LU,ALL

The LU in use is shown (for example, LLUN=MF1AP001)

Find the name of the VTAM procedure:
D A,L

In the next example, the VTAM procedure is called "VTAM2".

Start the VTAM procedure by tracing the APPC LU:
F VTAM2,TRACE,ID=MF1AP001,TYPE=BUF

In order to view the trace records, you must stop the GTF trace.

To stop the trace:
P IT

Format the trace under IPCS by using the following command with the GTF trace data set named as target.
GTFTRACE RNIO SLIP SVC USR JOBNAME(GDEDFM APPC)