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5.6 VSAM Differences
5.6.1 Introduction
This section covers the differences between OS/390 VSAM and VSE/VSAM. In
OS/390, the functions of VSAM and other OS/390 access methods are provided
by the OS/390 Data Facility Product (DFP). The term ICF refers to the Integrated
Catalog Facility. The term AMS refers to Access Method Services and/or the
program IDCAMS. All data set references are to VSAM data sets.
A complete set of DFSMS/MVS publications can be found in the
DFSMS/MVS
Library Guide
, GC26-4902 and
DFSMS/MVS General Information
, GC26-4900.
Planning information for Data Facility Systems Managed Storage (DFSMS) can
be found in the following manuals:
•
DFSMS/MVS General Information
, GC26-4900
•
DFSMS/MVS Planning for Installation
, SC26-4919
•
Implementing System-Managed Storage
, SC26-3123
•
Get DFSMS FIT: Fast Implementation Techniques
, SG24-2568
•
DFSMS FIT: Fast Implementation Techniques Process Guide
, SG24-4478
•
DFSMS FIT: Fast Implementation Techniques Installation Examples
, SG24-2569
•
RACF General Information
, GC23-3723
•
Getting Started with DFSORT
, SC26-4109
5.6.2 OS/390 Catalogs
At the time of writing, there are three catalog types supported in OS/390. After
the end of 1999, only ICF catalogs will be supported in the OS/390 environment.
The current catalog types are:
•
ICF catalogs - are the recommended catalog structures for your OS/390
system.
•
VSAM catalogs - these are similar and mostly compatible
5
to VSE/VSAM
catalogs. They do not provide the performance and recoverability of ICF
catalogs. They are not recommended for normal OS/390 production
operations. However, they do provide catalog portability between VSE and
OS/390. If used, they should be converted to ICF catalogs when the migration
is completed. Details on converting to ICF catalogs can be found in
Managing
Catalogs
, SC26-4914, chapter 9.
The VSAM catalog stores dates with two-digit years. VSE/VSAM has
implemented a sliding window interpretation of those dates. OS/390 (DFP)
has not made similar changes, and thus dates in VSAM catalogs will not be
correctly interpreted in OS/390 systems. Because of this, OS/390 (DFP) has
announced that VSAM catalogs will not be supported after December 31st
1999.
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Compatibility between VSE/VSAM catalogs and OS/390 VSAM catalogs is discussed in the section entitled 5.6.4, “OS/390 -
VSE/VSAM Catalog Compatibility” on page 117.
110 VSE to OS/390 Migration Workbook