Appendix C. Analysing CICS restart information

This section describes how you can programmatically determine the type of CICS® shutdown which occured, and whether it is safe to override the next restart type and perform a cold restart of the CICS system.

DFHRMUTL provides the SET_AUTO_START keywords to allow a CICS system to be auto-restarted with a given override. This can include AUTOCOLD, to make CICS perform a cold start. Care should be taken when performing such a change. A CICS system that was shutdown warm, and which had no indoubt, commit-failed, or backout-failed units of work (UOWs) keypointed at that time, can be restarted cold without loss of data integrity. However, if the system was not shutdown in a controlled manner, or there are such units of work recorded on the system log, a cold restart should not be performed, because system data integrity can be compromised.

To help you determine whether a cold start of the region system is appropriate or not, CICS provides the following information:

  1. The following DFHRMUTL summary information:
  2. A CICS global catalog record with the following VSAM KSDS key:
    X'00000011C4C6C8D9D4C4D440C4C6C8D9D4C4D46DD9C5E2E3C1D9E340'
    This record contains three fullword counts following the key. These are:
    1. The number of indoubt UOWs
    2. The number of commit-failed UOWs
    3. The number of backout-failed UOWs
    If any of these counts contains a number greater than zero, recovery information for these units of work is present on the CICS system log. In this case, a modification of the CICS autostart override record to AUTOCOLD is not appropriate, because system data integrity would be jeopardized.

    CICS deletes this global catalog record during restart, and writes it during a controlled shutdown. Therefore presence or absence of the record on the catalog indicates whether the CICS system was previously shutdown warmly (that is, by the use of CEMT PERFORM SHUTDOWN) or not. If the record exists on the global catalog, and the three count fields are zero, it is safe to use DFHRMUTL to modify the autostart override record to AUTOCOLD.

    Here is an example of this record, showing the presence of one indoubt unit of work at the time CICS was shutdown:

    KEY OF RECORD - 
    00000011C4C6C8D9D4C4D440C4C6C8D9D4C4D46DD9C5E2E3C1D9E340
    
    00000011C4C6C8D9D4C4D440C4C6C8D9D4C4D46DD9C5E2E3C1D9E34000000001 
    0000000000000000

    DSECTs for use by batch programs to map the global catalog record are provided, in C, COBOL, PL1, and Assembler. These are DFHRMREH, DFHRMREO, DFHRMREL, and DFHRMRED, respectively.

For more information about the DFHRMUTL utility, see the CICS Operations and Utilities Guide.

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