CICS® collects statistics on the data written to each journal and log stream which can be used to analyze the activity of a single region. However, because log streams can be shared across multiple MVS™ images, it can be more useful to examine the statistics generated by MVS.
Journalname statistics contain data about the use of each journal, as follows:
Note that the CICS system journalname and log stream statistics for the last three items on this list are always zero. These entries appear in journalname statistics to inform you of the journal type and log stream name for the special CICS system journals.
For more information on journalname statistics, see the CICS statistics tables in topic Journalname statistics.
Log stream statistics contain data about the use of each log stream including the following:
For more information on log stream statistics, see the CICS statistics tables in topic Logstream statistics.
Journalnames are a convenient means of identifying a destination log stream that is to be written to. CICS applications write data to journals using their journalname. CICS itself usually uses the underlying log stream name when issuing requests to the CICS log manager, and this must be considered when interpreting journalname and log stream resource statistics. For example, these may show many operations against a log stream, but relatively few, if any, writes to a journalname which maps to that log stream. This indicates that it is CICS that accesses the resource at the log stream level, not an application writing to it through the CICS application programming interface. These results can typically be seen when examining the journalname resource statistics for DFHLOG and DFHSHUNT, and comparing them with the resource statistics for their associated CICS system log streams.
For more information on logging and journaling, see Logging and journaling: performance considerations.
For information about the SMF Type 88 records produced by the MVS system logger, see the z/OS MVS System Management Facilities (SMF) manual.