Traces provided by VTAM

The VTAM® program provides several kinds of traces to record the flow of network events. Each trace occurs at a different point in the network (see Figure 1). This difference allows you to narrow down the problem by following a request/response unit (RU) through the network and determining where in the network the RU is incorrect. (The RU could be out of sequence or lost, the data in the RU could have been changed, and so on.)

This topic includes the following information:

Activating network traces
Starting the generalized trace facility (GTF)
Formatting and printing trace records
Trace output
The APPN route selection trace shows the flow of information throughout the APPN session setup route selection process. See APPN route selection trace for more information
VTAM traces and their results:
- The buffer contents trace shows the contents of inbound and outbound message buffers. See Buffer contents trace for more information.
- The I/O trace shows (in order) all I/O sent between VTAM and a particular network resource. See I/O trace for more information.
- The QDIOSYNC trace is used to synchronize host and OSA-Express2 or later diagnostic data. See QDIOSYNC trace for more information.
- The resource state trace creates VTAM internal trace (VIT) entries when the current state or desired state, or both, of a resource for which tracing has been requested changes. See Resource state trace for more information.
- The session management exit (SME) buffer trace shows the input and output of the session management exit (SME) ISTEXCAA. See Session management exit (SME) buffer trace for more information.
- The SMS (buffer use) trace shows information about the use of buffers, including how often a buffer pool has expanded, how many buffers are currently being used, and what was the maximum number of buffers used since the last trace record was written. See SMS (buffer use) trace for more information.
- The TGET/TPUT trace shows each message as it passes between a TSO command processor and TSO/VTAM. See TGET/TPUT trace for TSO/VTAM for more information.

The VTAM internal trace (VIT) is discussed in z/OS Communications Server: SNA Diagnosis Vol 2, FFST Dumps and the VIT.

Figure 1. Network traces provided by VTAM

Diagram that shows the VTAM program provides several kinds of traces to record the flow of network events.