HP 3000 Manuals HP 3000 Manuals
Conversion Issues
Most of the IBM/370 mainframe programs which you submit to this COBOL
system will be accepted syntactically and will run successfully.
However, there are a number of areas in which errors may occur.
It is probable that you will encounter few or none of these errors, but
if you do, following the suggested solutions will greatly reduce any work
involved in migrating your application. The known errors are detailed in
the following sections together with hints on how to overcome them.
General
Error Message Differences.
The default actions or assumptions made by this COBOL system after it has
issued W or E level error messages may differ from those made by the
IBM/370 mainframe Compiler.
Solution
You should either review all E and W level messages carefully, or modify
your source to remove the error(s).
Files not Supported.
IBM/370 BDAM and ISAM files and their corresponding language extensions
are not supported under this COBOL system.
Solution
Replace any BDAM files by ANSI relative files, and
any ISAM files by ANSI indexed files.
The DISK FULL Condition.
The file status value for the DISK FULL condition under this COBOL system
is not the same as that under IBM/370 mainframe COBOL. This COBOL system
returns a hexadecimal value of X3907. An IBM/370 mainframe program
returns a character value of 30.
Solution
Change your source program to reflect the changed value.
Arithmetic Operations.
Under IBM/370 mainframe COBOL, if you perform arithmetic operations on
non-numeric data, it causes a program check (data exception or 0C7).
Under this COBOL system, you must be sure the F run-time switch is set to
the default "+F".
Intermediate Result Precision.
This COBOL system uses the concept of two numeric registers designed for
worst-case calculation. This means that there are 18 decimal digits
(plus one for overflow) needed before the decimal point for rounding
capability during MULTIPLY and DIVIDE operations. There are also 18
decimal digits (plus one for overflow) needed for temporary overflow
during ADD and SUBTRACT operations. For this reason, intermediate result
calculations by this COBOL system are more accurate than in OS/VS COBOL
and VS COBOL II.
Solution
To ensure the same accuracy in these two dialects, you should replace
any COMPUTE statements with a series of operations using user defined
intermediate result fields. The size of each result will vary according
to the rules documented in the OS/VS COBOL and VS COBOL II manuals.
The COMPUTE Statement.
Results of a COMPUTE statement after an OVERFLOW condition are
incompatible between the mainframe environment and this COBOL system.
Solution
Use the ON SIZE ... clause if there is a possibility of numeric
OVERFLOW. You should never depend on the result if this condition occurs.
PIC 9 Items.
PIC
If your source program contains PIC 9(n) DISPLAYDISPLAY usage data items
which contain spaces, it may fail at run-time.
ACCEPT Statements.
An IBM/370 mainframe COBOL ACCEPT statement from SYSIN is not supported
by this COBOL system.
Solution
For larger amounts of data (that is, a set of parameter cards) you should
define a new sequential file. For a single ACCEPT of a small amount of
data, enter the input data on the operating system command line when you
invoke the application, then in the program use the syntax:
ACCEPT data-name FROM COMMAND-LINE
DISPLAY Statements.
An IBM/370 mainframe COBOL DISPLAY statement to SYSOUT (or any other
DDNAME) is not supported by this COBOL system.
Solution
All DISPLAY's are directed to the terminal (console). If you are using
the PC-DOS system, this allows you to redirect this output to a file if
you request it at the time the application is invoked. See the PC-DOS
Reference Manual for further details of redirection.
The SIGN SEPARATE Clause.
When you download input data from an IBM/370 mainframe which contains
signed numeric USAGE DISPLAY data items without the SIGN SEPARATE clause,
embedded signs are not interpreted correctly.
Solution
Set the SIGN(EBCDIC) system directive when you submit your programs to
this COBOL system. This causes this COBOL system to output code which
interprets signed data by using
EBCDIC rather than ASCII convention. See your COBOL System Reference for
details of this directive.
Comparisons of Alphanumeric Data.
Comparisons of alphanumeric data under this COBOL system are not the same
as those under IBM/370 mainframe COBOL.
Solution
Set the NATIVE(EBCDIC) system directive when you submit your programs to
this COBOL system. This causes this COBOL
system to output code which interprets signed data by using the EBCDIC
rather than the ASCII convention. See your COBOL System Reference for
details of this directive.
Pointer Variables (VS COBOL II Only).
Under this COBOL system, when you redefine a VS COBOL II POINTER variable
as a COMP field, and make an arithmetical calculation on this field to
change the value of the POINTER, its behavior will not be the same as
under IBM/370 COBOL.
Solution
The problem is because in this COBOL system, the POINTER has a format
defined by the 8086 machine architecture, whereas the VS COBOL II POINTER
uses the 370 machine architecture.
This COBOL system provides syntax within the SET statement which enables
you to change the value of a POINTER. See your Language Reference for
details on how to do this.
File Input and Output
File Referencing.
IBM/370 mainframe COBOL programs reference data files indirectly via
DDNAME's. This function is not implemented in this COBOL system.
Solution
To emulate this function, use the ASSIGN(EXTERNAL) directive when you
submit your program to this COBOL system. Before execution, you can
associate the data file names used in your program
with physical files via the operating system SET command.
For example, if your program contains the line:
SELECT IN-FILE ASSIGN TO UT-S-INFILE.
and your data file is called C:INFILE.DAT, you enter the command:
SET INFILE=C:INFILE.DAT
which will establish the appropriate connection between the data file
name and your application program.
The NOMINAL KEY Clause.
The mainframe COBOL NOMINAL KEY IS ... clause for relative and indexed
files is not supported by this COBOL system.
Solution
For both types of file, replace the NOMINAL KEY IS ... clause with
the ANSI standard RECORD KEY IS ... clause. Also, for indexed files,
you should change any Procedure Division references to nominal key in
your source programs so that they reference record key.
The ACTUAL KEY and TRACK-LIMIT Clauses.
The mainframe COBOL ACTUAL KEY IS ... and TRACK-LIMIT IS ... clauses in
direct files are not supported by this COBOL system.
Solution
Convert any direct files to relative files as the ACTUAL KEY IS ...
clause closely resembles the RECORD KEY clause of relative files. You
can then, in most cases, delete the TRACK-LIMIT clause.
The TRACK AREA Clause.
The TRACK AREA IS ... clause for indexed files is not supported by this
COBOL system.
Solution
You should delete this clause from your source program. TRACK AREA
was an IBM extension used to improve performance of ISAM during
random updates. Indexed files in this COBOL system, like mainframe VSAM
files, are reorganized as they are updated.
Deleting Records.
When you have successfully submitted your programs to this COBOL system,
you may find that on execution you cannot delete records in relative
files.
Solution
In IBM/370 systems, you can usually delete records in relative files
by moving HIGH-VALUES to a delete byte and rewriting the record. The
ANSI standard does not require (or use) an explicit delete byte.
Therefore, you must change the syntax in your source
program so that a DELETE operation is performed on the record.
Record Lengths.
This COBOL system checks both the minimum and maximum record lengths File
of a variable length file when it is opened. The file status is
automatically set to "39" if the attributes do not match. However, the
mainframe environment only checks the maximum length value.
Solution
Review the File Description (FD) record descriptions to ensure that all
programs referencing a variable length file use the same minimum and
maximum values.
Inter-program Communication
Calls to Subprograms.
Calls to subprograms using this COBOL system default to dynamic linkage,
whereas calls to subprograms on a IBM/370 mainframe default to static
linkage g;static.
Solution
Specify the NODYNAM system directive when you submit your source program
to this COBOL system; this will cause any CALL operations to be static.
See your COBOL System Reference for further details of this directive.