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CICS also writes “backout-failed” records to the system log if a failure occurs in
backout processing of a VSAM data set during dynamic backout or emergency
restart backout.
Records on the system log are used for cold, warm, and emergency restarts of a
CICS region. The only type of start for which the system log records are not used is
an initial start.
System activity keypoints
The recovery manager controls the recording of keypoint information, and the
delivery of the information to the various resource managers at emergency restart.
The recovery manager provides the support that enables activity keypoint
information to be recorded at frequent intervals on the system log. You specify the
activity keypoint frequency on the AKPFREQ system initialization parameter. See the
CICS System Definition Guide for details. Activity keypoint information is of two
types:
1. A list of all the UOWs currently active in the system
2. Image-copy type information allowing the current contents of a particular
resource to be rebuilt
During an initial phase of CICS restart, recovery manager uses this information,
together with UOW-related log records, to restore the CICS system to its state at
the time of the previous shutdown. This is done on a single backward scan of the
system log.
Frequency of taking activity keypoints: You are strongly recommended to specify a
nonzero activity keypoint frequency. Choose an activity keypoint frequency that is
suitable for the size of your system log stream. Note that writing activity keypoints
at short intervals improves restart times, but at the expense of extra processing
during normal running.
The following additional actions are taken for files accessed in non-RLS mode that
use backup while open (BWO):
v Tie-up records are recorded on the forward recovery log stream. A tie-up record
associates a CICS file name with a VSAM data set name.
v Recovery points are recorded in the integrated catalog facility (ICF) catalog.
These define the starting time for forward recovery. Data recorded on the
forward recovery log before that time does not need to be used.
Forward recovery logs
CICS writes VSAM forward recovery logs to a general log stream defined to the
MVS system logger. You can merge forward recovery log data for more than one
VSAM data set to the same log stream, or you can dedicate a forward recovery log
stream to a single data set.
See “Defining forward recovery log streams” on page 116 for information about the
use of forward recovery log streams.
User journals and automatic journaling
User journals and autojournals are written to a general log stream defined to the
MVS system logger.
22 CICS TS for z/OS 4.1: Recovery and Restart Guide