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This provides cross address space sharing as well as journaling and recovery
for the batch applications. It also allows existing files to be accessed with new
application tools such as QMF without having to rewrite existing applications.
5.6.7 Programming Languages and VSAM Support
For additional information on program languages and VSAM considerations, see
the various language chapters in this publication. In addition, each of the
languages has its own publication library generally including migration guides as
well as reference manuals. These manuals should be consulted for additional
information if necessary.
5.6.7.1 COBOL for OS/390 & VM
IBM COBOL for OS/390 & VM is generally source-compatible (in terms of the
VSAM function provided) with IBM COBOL for VSE. Both compilers provide
similar support for VSAM KSDS, ESDS, RRDS, Alternate Index (AIX) path
processing, and reusable data sets. Chapter 12, “COBOL” on page 249 contains
more information.
5.6.7.2 OS/VS COBOL
See Chapter 12, “COBOL” on page 249, for details of DOS/VS COBOL and
OS/VS COBOL migration requirements.
5.6.7.3 RPG II
IBM OS/VS RPG II (5740-RG1) is generally compatible with VSE RPG II (5746-RGI)
Release 3. However, OS/VS RPG II is not supported with CICS/OS or IMS/VS
HLPI. OS/390 VSAM does not allow an empty cluster to be opened for input;
VSE/VSAM permits this operation for SAM-ESDS workfiles only.
5.6.7.4 PL/I
PL/I for OS/390 and PL/I for VSE are essentially compatible in terms of VSAM
function, and are generally considered source language compatible.
5.6.7.5 Assembler
For a discussion of Assembler programming considerations, see Chapter 13,
“Assembler” on page 267.
5.6.8 VSAM Error and Reason Code Compatibility
OS/390 VSAM Error codes and reason codes may have a slightly different
meaning than VSE/VSAM. In all cases, OS/390 documentation should be
consulted such as the
DFSMS/MVS DFSMSdfp Diagnosis Reference
, LY27-9606.
Especially in Assembler, the logic for specific error codes should be verified. In
some cases, OS/390 VSAM provides additional information.
5.6.9 DFSORT and VSAM Considerations
Sorting of VSAM files with DFSORT for VSE or VSE SORT/MERGE Version 2 and
with OS/390 DFSORT should be compatible with the following two exceptions:
1. Sorting or merging FROM and TO the same (reusable) VSAM data set. (This
is often referred to as a suicide sort.)
This function is supported in VSE DFSORT and VSE Sort/Merge, but not
supported in OS/390 DFSORT. A suggested circumvention is to sort the
VSAM data set to a temporary data set (either VSAM or non-VSAM) and then
Chapter 5. Disk and Tape Storage Considerations 131