This section describes how to manage the size of logs.
Normally, you should allow the CICS® log manager to manage
the size of the system log. You should not need to take explicit
action to delete redundant data, nor to retain data--all system
log data required on a restart is presented, providing the necessary
completed unit of work information. If you do need
to retain system log data beyond the time it would normally be deleted
by CICS, see the CICS Transaction Server for z/OS® Installation Guide for
advice on how to define your system log.
Versions of MVS before OS/390 Release
3
- The MVS™ system logger imposes a limit of 168 data sets
per log stream.
- There is no mechanism for the automatic deletion of records from
general log streams. It is your responsibility to delete such data
to prevent the 168 data set limit being exceeded.
If you need longer-term
data retention, then you must copy the data from log stream storage
into alternative archive storage. See Example 3 for an
example of the JCL you would need in a job to copy log stream data
to archive storage, and then delete it from the log stream.
Although
message IXG257I is issued when 90% of the log stream has been
filled, this event is not detectable by CICS. You should use your
automation software to monitor occurrences of this message.
OS/390 Release 3 and later
- The number of data sets per log stream recognized by the MVS logger
is several million. In normal circumstances, you do not need to be
concerned about the limit being reached.
- You can cause data to be retained on a log stream for a specified
period, and then deleted automatically. To arrange this for general
log streams, define the logs to MVS with AUTODELETE(YES) and RETPD(dddd),
where dddd is the number of days for which data is to be
retained. This causes the MVS system logger to delete an entire log
data set when all the data in it is older than the retention period
(RETPD) specified for the log stream.
Note:
Support for the removal of the 168 data set limit,
and for the AUTODELETE and RETPD parameters, requires the sysplex’s
LOGR couple data set to have been formatted using OS/390® Release
3 or later. The removal of the 168 data set limit also requires the
LOGR data set to have been formatted with DSEXTENT(nnnnn). If either
has not been done, refer to the "Pre-OS/390 Release 3" box.
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