Planning log streams for use by your log of logs (DFHLGLOG)

The log of logs is written by CICS® to provide information to forward recovery programs such as CICS VSAM Recovery.

The log of logs is a form of user journal containing copies of the tie-up records written to forward recovery logs. Thus it provides a summary of which recoverable VSAM data sets CICS has used, when they were used, and to which log stream the forward recovery log records were written.

If you have a forward recovery product that can utilize the log of logs, you should ensure that all CICS regions sharing the recoverable data sets write to the same log of logs log stream.

  DEFINE GROUP(JRNL) DESC('Merge log of logs')
         JOURNALMODEL(DFHLGLOG) JOURNALNAME(DFHLGLOG) TYPE(MVS)
         STREAMNAME(&USERID..CICSVR.DFHLGLOG)

Note: Note that this definition is supplied in group DFHLGMOD in DFHLIST.

If you don't have a forward recovery product that can utilize the log of logs you can use a dummy log stream:

  DEFINE GROUP(JRNL) DESC('Dummy log of logs')
         JOURNALMODEL(DFHLGLOG) JOURNALNAME(DFHLGLOG) TYPE(DUMMY)

In addition to forward recovery, the log of logs is also used for recording log stream errors. When a log stream failure occurs, CICS tries to update the log of logs with the error and diagnostic information, unless DFHLGLOG is defined as TYPE(DUMMY).

Do not share the log of logs between test and production CICS regions, because it could be misused to compromise the contents of production data sets during a restore.