Understanding MVS log streams
Coupling facility log streams reside in the coupling facility and
in either a data space in the IXGLOGR address space or in staging data sets.
DASD-only log streams reside in a data space in the IXGLOGR address space
and in staging data sets.
Defining system log streams
You must define a system log if you want to preserve data integrity
in the event of unit of work failures and CICS failures.
Defining forward recovery log streams
VSAM data sets that are defined as recoverable files must have
associated forward-recovery logs. In the event of physical failure or corruption, CICS VR
can reapply the updates.
Defining the log of logs
The log of logs is an MVS log stream created by CICS TS that
contains records that are written each time a file is opened or closed.