IBM OS/390 User Manual
Chapter 14. RPG II
14.1 Migration from VSE to OS/390
The aim has been to make it easy to convert programs running under VSE to run
under OS/390, with the minimum of changes to the source code. In fact, the
source programs will run unmodified, except for the following:
under OS/390, with the minimum of changes to the source code. In fact, the
source programs will run unmodified, except for the following:
•
The command level interfaces with CICS/VS and DL/I VSE are not supported
by OS/390 RPG II. They must not be specified on the Header Specifications
form, and calculations that refer to CICS/VS and DL/I must not be entered on
the Calculation Specifications form.
by OS/390 RPG II. They must not be specified on the Header Specifications
form, and calculations that refer to CICS/VS and DL/I must not be entered on
the Calculation Specifications form.
•
Combined files do not exist in OS/390 RPG II. Such files must not be
specified on the File Description Specifications form.
specified on the File Description Specifications form.
As explained below, many entries that are necessary for an RPG II program to
run under VSE are ignored by OS/390. The compiler will issue a warning
message, but will still produce object code.
run under VSE are ignored by OS/390. The compiler will issue a warning
message, but will still produce object code.
When using spooled print files (JES2/JES3) with overflow printing you must use
line counter specification, because channel 12 is not sensed.
line counter specification, because channel 12 is not sensed.
Note
As an application development tool, you should consider adopting other
application language enabling facilities which tend to take better advantage
of S/370 architecture and MVS/XA, MVS/ESA environments; for example,
COBOL, PL/I, CSP, FORTRAN.
application language enabling facilities which tend to take better advantage
of S/370 architecture and MVS/XA, MVS/ESA environments; for example,
COBOL, PL/I, CSP, FORTRAN.
14.1.1 Device Information
OS/390 allows data management information to be provided at object time by
means of DD statements. Parameters such as record and block size, label
information, or definition of disk space, can thus be changed without affecting the
source code. The entry of these parameters on the File Description
Specifications form is optional; JCL specifications are recommended.
means of DD statements. Parameters such as record and block size, label
information, or definition of disk space, can thus be changed without affecting the
source code. The entry of these parameters on the File Description
Specifications form is optional; JCL specifications are recommended.
Also optional under OS/390 is the definition of physical and logical device; the
only device types that must be specified are CONSOLE and SPECIAL.
only device types that must be specified are CONSOLE and SPECIAL.
14.1.2 Print Files
1. For print files controlled by a line counter, without block length specification,
RECFM must be specified in the JCL. LRECL is the record length specified in
the file description specification plus 1 (for the machine control character).
the file description specification plus 1 (for the machine control character).
2. For print files controlled by a line counter with block length specification, the
RECFM in the DCB is the file format specified in the file description
specification with machine control characters; it cannot be overwritten by
JCL.
specification with machine control characters; it cannot be overwritten by
JCL.
3. For print files without line control specifications and with block length
specified in file descriptions:
Copyright IBM Corp. 1998
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