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EXTEND (Extend Data or Index Areas) › EXTEND › How Space Is Allocated for an EXTEND

How Space Is Allocated for an EXTEND

The additional space into which a database data area or index area is to be extended can be allocated in one of three ways:

  1. You can increase the number of tracks in the last extent statement of the current extents, if space exists immediately after the current last extent.
  2. You can add one or more additional extent statements after the current extent statements. New extents can never be added to a volume with current extents, except the last volume.
  3. You can move the data or index area to another larger data set on another volume of the same device type. This move should be done as a backup/restore process. Non-CA Datacom/DB programs exist to accomplish this move also.

    The EXTEND function compares, in this case, information from the current extents to the control record information. EXTEND then formats any new blocks based on the extent information from the IBM OPEN. The function updates the control record to reflect the new block count.