Справочник Пользователя для IBM OS/390

In predecessors of today

′

s OS/390 systems, it was not uncommon to use JCL

DD statements specifying user catalogs to be used for a job or a step
(JOBCAT or STEPCAT). This procedure was obsoleted with the advent of the
Integrated Catalog Facility and its ALIAS mechanism, and it should not be
used.

The OS/390 JOBCAT and STEPCAT DD statements when used in jobstreams,
bypass the normal catalog search technique via the ALIAS. Their use can
cause incorrect cataloging of duplicate 

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new

″ 

data sets. In addition, these

statements are not supported by Data Facility Systems Managed Storage
(DFSMS). JOBCAT and STEPCAT should not be used when migrating to
OS/390.

Even though (non-concurrent) sharing of VSAM between VSE and OS/390 is
described below, it is recommended that this practice not be extended past
the migration period. As VSAM changes are probable with new releases of
OS/390 DFP or VSE/VSAM, 

″

flip flopping

″ 

of data sets and catalogs between

VSE and OS/390 should be limited to the migration period.

Note that VSAM catalog dates are stored with a two-digit year representation.
Although VSE/VSAM has been updated to interpret these dates using sliding
window technologies, DFP/VSAM has not been changed similarly. DFP/VSAM
use of VSAM catalogs will not function correctly after December 31st 1999.

See the WSC flash article Figure 8 on page 113.

A VSE/VSAM master or user catalog can be designed (DEFINEd) to be
compatible and therefore accessible by an OS/390 system. 

catalogs may be ported between environments. For a VSE/VSAM catalog to be
compatible (and used in an OS/390 system), the catalog has to have the
following characteristics:

 1. The catalog was defined with the IMBED option.

This is the VSE/VSAM default, but many users specify NOIMBED for space
savings within the catalog itself.

 2. The catalog is on a device supported by OS/390.

Generally, the disk devices not supported by OS/390 are FBA Direct Access
Storage Devices.

Note that non-VSAM data sets within VSAM data spaces, such as
VSE/VSAM-managed SAM files, cannot be accessed in OS/390.

Chapter 5. Disk and Tape Storage Considerations