IBM SC34-7012-01 manual Log of logs failure, Reading log streams offline, About this task

About this task

The CICS-supplied group, DFHLGMOD, includes a JOURNALMODEL for the log of logs, called DFHLGLOG, which has a log stream name of &USERID..CICSVR.DFHLGLOG. Note that &USERID resolves to the CICS region userid, and if your CICS regions run under different RACF user IDs, the DFHLGLOG definition resolves to a unique log of logs log stream name for each region. However, a separate log of logs is not recommended for recovery products such as CICS VSAM recovery, and you should consider defining a log stream that is shared between CICS regions within the same CICSplex. For example, you might define one log stream for all the CICS regions that are members of the same production CICSplex, and another for test regions, choosing a high-level qualifier that reflects the scope of the log of logs. Using a CICSplex-wide log stream for the log of logs is particularly important if you are using VSAM RLS and multiple CICS application-owning regions have direct access to the same data sets.

The log of logs contains records that are written each time a file is opened or closed. At file-open time, a tie-up record is written that identifies:

vThe name of the file

vThe name of the underlying VSAM data set

vThe name of the forward recovery log stream

vThe name of the CICS region that performed the file open.

At file-close time, a tie-up record is written that identifies:

vThe name of the file

vThe name of the CICS region that performed the file close.

The log of logs assists forward recovery utilities to maintain an index of log data sets.

Log of logs failure

If a log of logs fails, CICS issues a message, but ignores the error.

Further attempts to write to the log of logs are ignored. Forward recovery programs that use the log of logs for performance optimization must not use the log of logs following a failure. The most likely cause of a log of logs failure is a definition error, in which case the failure is unlikely to affect production data sets.

Reading log streams offline

Access to MVS system logger log stream data is provided though the subsystem interface (SSI) with the LOGR subsystem.

About this task

To use the SSI to gain access to the log stream data, specify LOGR on the SUBSYS parameter on the log stream DD statement. Specifying the LOGR subsystem name on the SUBSYS parameter enables LOGR to intercept data set open and read requests at the SSI, and convert them into log stream accesses.

Depending on the options specified on the SUBSYS parameter, general log stream records are presented either:

vIn a record format compatible with utility programs written for releases of CICS that use the journal control program, DFHJUP, for logging and journaling

Chapter 11. Defining system and general log streams 119