Buffer contents trace operation

Make sure that the GTF with the TRACE=USR option is active before starting this trace. See Starting the generalized trace facility (GTF).

If you are using VTAM® CMIP services or the VTAM topology agent, a large amount of data is traced. Therefore, you should increase the value of the GTF BLOK parameter and the GTF REGION parameter. For example, specify BLOK=400 and REGION=0 (to indicate no limit on region size). You should also specify the AMOUNT=FULL operand on the TRACE command for the buffer trace so that the entire CMIP string is traced.

Note: If the GTF does not have enough storage to record all the segments, it might record only the last segment. The GTF will report the number of lost records. You might want to increase the storage available to the GTF to avoid losing records.

Start the buffer contents trace with the MODIFY TRACE command or the TRACE start option.

Specify:	To trace:
ID=nodename	Requests and responses flowing between VTAM and nodename.
ID=ISTNOTIF	Event notification activity between the VTAM topology agent and notification services of CMIP services. Specify the AMOUNT=FULL operand when you start the trace.
ID=ISTPUS	Request and response units (RUs) for sessions between the host physical unit and another physical unit type 4 or 5. (These RUs include ER-ACT, ER-OP, and ER-TEST RUs.)
ID=ISTTOPAG	Requests and responses to and from the VTAM topology agent. Specify the AMOUNT=FULL operand when you start the trace.
ID=VTAM	Request and response units (RUs) for SSCP sessions.

If you use the SCOPE=ALL or EVERY operand when you start the trace, VTAM records messages to and from the specified node and all its valid subnodes.

Note: You cannot use the SCOPE=ALL or EVERY operands with ID=ISTPUS.

For more information on the MODIFY TRACE command, see z/OS Communications Server: SNA Operation. For more information on the TRACE start option, see z/OS Communications Server: SNA Resource Definition Reference.

To format and print buffer contents trace output, use ACF/TAP or IPCS.

For more information, see Formatting and printing trace records.