CF structures
This might affect Task 10 in Customizing your queue managers.
WebSphere MQ local queue objects defined with QSGDISP(SHARED) have their messages stored on a Coupling Facility (CF) list structure so that they can be accessed by any other queue managers within the queue-sharing group.
As with the CFSTRUCT attribute of queues, the name is specified without the initial four-character queue-sharing group name that forms the name used by z/OS.
WebSphere MQ V6.0 supports large messages on shared queues (up to 100 MB) and uses DB2 to store data from those messages. CF structures supporting large shared queue messages must have the new CFLEVEL(4).
CFLEVEL(4) function
Shared queues defined on a CFLEVEL(4) CF structure can hold messages of up to 100 MB. Shared queues of a lower CFLEVEL can only hold messages of up to 63 KB.
A CFSTRUCT with CFLEVEL(4) can only be backed up or recovered by a V6 queue manager. CF structure objects defined with CFLEVEL(4) are only usable by V6 queue managers.
CFLEVEL(3) functions
Queues defined on a CFLEVEL(3) CF structure can have the INDXTYPE(GROUPID) attribute.
Persistent messages can be stored on a queue defined on a CF structure with CFLEVEL(3) and the RECOVER(YES) attribute. The MQSC commands BACKUP CFSTRUCT and RECOVER CFSTRUCT are provided to support recovery. Ensure that regular backups of such structures are taken.
To use the RECOVER CFSTRUCT command, all the active and archive log data sets, and bootstrap data sets of each queue manager in a queue-sharing group must be accessible to each other. You must ensure that your security setup allows this, and use Access Method Services to change the SHAREOPTIONS of these data sets to be (2 3), for example:
ALTER '++hlq++.logcopy.ds01.data' SHAREOPTIONS (2 3)For information about other CFLEVELs, see the DEFINE CFSTRUCT command in WebSphere MQ Script (MQSC) Command Reference.
Recommendations
Once all queue managers in the queue-sharing group have been migrated to V6, alter all CF structure objects to have at least CFLEVEL(3). This gives greater resilience in the unlikely event of a Coupling Facility structure failure, as V6 queue managers can tolerate the failure of a CFLEVEL(3) CF structure.