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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:
v The name of the file
v The name of the underlying VSAM data set
v The name of the forward recovery log stream
v The name of the CICS region that performed the file open.
At file-close time, a tie-up record is written that identifies:
v The name of the file
v The 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.
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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:
v In 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