Collecting trace data
CICS application traces are activated and terminated transparently to tasks as needed to satisfy trace requests.
The trace data collection is activated or deactivated whenever such requests are sent from the BBI-SS PAS to CICS.
The type of trace records that are produced depends on whether the SUMMARY or DETAIL option is specified in the trace request.
The data extractor must be active to perform summary or detail tracing. A detail trace uses the CICS global user exits XEIIN and XEIOUT to trace all EXEC CICS API and SPI calls that are issued by a transaction. A detail trace traces only transactions that started after the trace is started, unless this is an in-flight transaction trace. A summary trace traces all the transaction history records that were written after the trace was started, even if the transaction was started before the summary trace.
Trace data is stored in a trace data space in the PAS address space. There is one trace data space for each CICS target that has an active application trace. The data space is not created until an application trace is started for a CICS target, and the data space is deleted when the last application trace for that CICS is purged. For information about specifying the size of the trace data space, see Customizing-the-application-trace-facility.
For each transaction that is eligible to be traced in an active detail application trace, two data space buffers are allocated to hold trace events: one for summary trace and one for detail trace. The size of the buffers is either 48 KB or the TRSIZE value. The TRSIZE value is used if DLOGPROC=TRSIZE is specified in CMRSOPT.
If the buffers become full and trace logging is not enabled for this trace, trace events will be lost. If logging is enabled, a full buffer is written to the log data set before the buffer is reused. One indication that data has been lost or been written to the log data set is if the first trace event in the DTRAC view (accessed from the STRAC view via the CT view) is not a START-PROGRAM event. The buffered data for an active trace can be accessed from the the CT view after the CICS tasks that are being traced have terminated unless the data space storage reserved for the trace has wrapped.
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