The INIT function has been enhanced as follows.
A new option, OPTION1=REINIT, can be used during initialization to "re-initialize" an index area or data area. Specifying OPTION1=REINIT requires that you also specify VERIFY=YES.
OPTION1=REINIT causes history information in the control block to be retained. Without OPTION1=REINIT, all history data is removed.
When using OPTION1=REINIT, the data set is re-initialized with the same number of tracks that were in use before the INIT, and no additional tracks are found or added to the data set during the INIT. When OPTION1=REINIT is not specified, the INIT closes the data set for update, opens the data set for output (honoring current, complete JCL specifications), closes the data set for output, then reopens the data set for update.
Adding space to an index or data area is normally accomplished using a DBUTLTY EXTEND function, but it can be done during an INIT function as well. A benefit of the OPTION1=REINIT for z/OS users is that it allows unused volumes to be added to data sets that do not have to be removed before an INIT. For example, in a z/OS environment, if you are not using SMS, you could INIT an area on 3 volumes and load the area. You might then manually uncatalog the area and recatalog it with an additional volume or volumes. Those additional volumes would be available for any dynamic extend for the area that was needed, but to prevent the INIT from forcing the use of the volumes that were added solely for the use of dynamic extend, you would need to manually uncatalog the area before another INIT and recatalog it without any additional volumes.
A benefit of OPTION1=REINIT for z/VSE users is that unexpired files do not have to be deleted.
With the INIT function VOLUMES=n, you can specify the maximum number of volumes to initialize. Without the VOLUMES= option, the number of volumes having specific VOLSER information is initialized. The VOLUMES= option allows more volumes to be cataloged as part of the data set and made available to a DBUTLTY EXTEND or dynamic EXTEND, while being effectively held in reserve without a specific allocation. For example, you could specify VOLUMES=3 when using an INIT to initialize an area that needs three volumes, intending to only initialize the space on three volumes. But the JCL could specify six specific volumes, for example, VOL=SER=(VOL001,VOL002,VOL003,VOL004,VOL005,VOL006), so that volumes 4, 5, and 6 are not allocated or used during the INIT but are available to a dynamic extend. In this case, the extra volumes would not need to be removed before another INIT.
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