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At intervals, CICS itself checks for the availability of the MVS logger. It uses one of two procedures to perform these checks, depending on your operating system.

  • If you are using OS/390 Release 2.10 or z/OS Release 1.1, and the MVS logger PTF UW79565 has been applied, CICS checks by querying the system log connection status. This is the more efficient of the two procedures.

  • If your operating system does not meet these conditions, CICS checks by initiating a BROWSE START operation on the system log.

If the check fails, CICS either abends or quiesces, depending on the returned MVS logger reason code.

The interval at which CICS checks for the availability of the MVS logger varies, depending on the amount of system logging activity in the CICS region. The first check is made after CICS has not made contact with the MVS logger for 10 seconds. If CICS continues to perform no system logging after the first check, the interval between checks doubles each time, up to a maximum of 600 seconds. If CICS makes contact with the MVS logger at any point, the interval between checks is halved, down to a minimum of 10 seconds.

The checking interval can be affected by the exit time interval specified in the ICV system initialization parameter, as follows:

  • If the value specified in the ICV system initialization parameter is less than 10 seconds, it has no effect on the checking interval.

  • If the value specified in the ICV system initialization parameter is greater than 10 seconds but less than 600 seconds, the checking interval varies between the value specified in the ICV system initialization parameter, and 600 seconds. The first check is made after an interval corresponding to the value in the ICV system initialization parameter, instead of being made after 10 seconds. The minimum checking interval is the value in the ICV system initialization parameter.

  • If the value specified in the ICV system initialization parameter is greater than 600 seconds, the checking interval does not vary, and always corresponds to the value in the ICV system initialization parameter.

The statistics field IGXQUERY in the CICS log manager statistics enables you to monitor the number of checks that CICS makes for the availability of the MVS logger.