z/OS Communications Server buffer tracing

Use z/OS Communications Server (VTAM) buffer trace to investigate terminal incorrect output errors in a VTAM environment. For example, z/OS® Communications Server SNA buffer tracing enables you to look at all the data that is passed between logical units on an SNA communication link. The trace entries, which include the netname of the terminal to which they relate, are made to the GTF trace data set. If you want to send “normal” CICS® trace entries there, you can rationalize the activities of CICS with the asynchronous activities of SNA.

Starting trace

Step 1. Start GTF trace under MVS

Enter the following MVS commands:

S GTF.identifier
R yy,TRACE=USRP,JOBNAMEP
R yy,USR=(F6C,FF1,FE1,FEF),JOBNAME=cicsjob,END
R yy,U

where yy is the number of the message.

User trace ID F6C is for CICS trace, FF1 is for VTAM buffer trace (user or API component), FE1 is for VTAM internal trace, and FEF is for VTAM buffer trace (TSC component). For a full list of trace options, see GTF trace options in the z/OS MVS Diagnosis: Tools and Service Aids guide.

Step 2. Turn on VTAM buffer trace and VTAM internal trace

Enter the following MVS command:

F NET,TRACE,TYPE=BUF,ID=applid,AMT=FULL,E 
F NET,TRACE,TYPE=VTAM,MODE=EXT,OPT=(API,PIU,MSG,SSCP)

where applid is the CICS applid.

Re-create the failure or problem.

Stopping trace

Enter the following MVS commands to turn off VTAM trace:

F NET,NOTRACE,TYPE=VTAM,OPT=END
F NET,NOTRACE,TYPE=BUF,ID=applid

Enter MVS command Stop identifier to stop GTF trace. For instructions, see Stopping GTF in the z/OS MVS Diagnosis: Tools and Service Aids Guide.

Formatting trace

Use IPCS with the GTFTRACE option to format the trace. For example, enter the following from IPCS:

Enter 0 to display the Defaults panel.
Enter the trace dataset name:
```
Source ==> DSNAME('trace.dataset.name')
```
Enter =6 to display the Command panel.

Enter one of the following commands:

To format all trace:
```
==> GTFTRACE USR(ALL)
```
```
==> GTFTRACE JOBNAME(cicsjob) USR(F6C)
```
```
==> GTFTRACE USR(F6C,FF1,FE1,FEF)
```
To format VTAM TSC trace:
```
==> GTFTRACE USR(TPIO)
```

Interpreting trace

See VTAM trace record formats for help.