Events that trigger a rebuild of partition definition control blocks

IMS checks the HALDB change version numbers to detect changes to partition definitions.

IMS rebuilds the internal partition definition control blocks, if necessary, in the following events:

• When a partitions are authorized for use, which detects changes in existing partitions or in partitions that are not already authorized. This situation occurs commonly when a partition is taken offline, changes are made to its definition in the RECON data set, and the partition is made available again. The first use of the updated partition triggers the rebuild of the partition definition control blocks.
• When an invalid key is detected by partition selection or by a partition selection exit routine, such as when a new partition is added beyond the high key of the last partition and all existing partitions are already authorized. In this case, IMS partition selection or the partition selection exit routine detects the new partition and IMS rebuilds the partition definition control blocks automatically.
• When a /START DB HALDB_Master OPEN or UPDATE DB NAME(HALDB_Master) OPTION(OPEN) command is issued. For example, if a new partition is added beyond the high key of the last partition and all existing partitions are already authorized, these commands initiate a rebuild of the partition definition control blocks.