
ISAM Datasets
User Reference
Connectivity Systems, Inc.—Copyright © 2006
Use Pursuant to Company Instructions
7-27
ISAM Datasets
Description BIM-EPIC can control ISAM datasets. The following MVT restrictions
affect BIM-EPIC ISAM dataset processing.
Note:Note:
VSE no longer supports ISAM. The following restrictions apply only to
MVT and MVT/VSE.
BIM-EPIC can control only one prime data area, one overflow
area, and one index per ISAM dataset.
ISAM datasets are automatically allocated on cylinder
boundaries.
If UNCDSK=YES is specified as a configuration option or if you
specify DLBL options in your JCL, uncontrolled ISAM datasets
are limited to a maximum of 5 extents total.
DSN Catalog There are no special requirements for the catalog entry. The extent size
specified in the catalog refers to the prime data area. Multiple extents are
not allowed. Extent information for the index and overflow are taken
from the JCL. The disk pool applies to all prime data, index, and overflow
areas.
JCL
Requirements
EXTENT statements are always required for the prime data, index, and
overflow areas.
For catalog controlled datasets, the number of tracks to allocate for the
prime area is taken from the catalog, unless you specify the DLBL, option
code O. The number of tracks to allocate for index and overflow areas
must be specified on the appropriate extent statement, as shown in the
following examples:
// DLBL MASTER,'EPIC.ISAM.MASTER.FILE',,ISE
// EXTENT SYS040,,4,1 Index
// EXTENT SYS041,,1,2 Prime
// EXTENT SYS042,,2,4 Overflow
// DLBL MASTER, 'EPIC.ISAM.MASTER.FILE',,ISC
// EXTENT SYS040,,4,1,,15 Index
// EXTENT SYS041,,1,2 Prime
// EXTENT SYS042,,2,4,,30 Overflow
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