On May 25, 2005, at 1:21 AM, Paul Gilmartin wrote:
In a recent note, Norbert Friemel said:
Date: Tue, 24 May 2005 17:00:02 -0500
Yes. From the dusty "IBM OS Full American National Standard COBOL,
GC28-6396-5, Revised 12/1/75 by TNL GN26-0808, p. 234":
...
At execution time, the USING option may be used to pass parameters
from the
EXEC job control statement to a main COBOL program. In this case, a
USING
option on the Procedure Division header of a main program may contain
identifier-1 as its only operand. Information from the PARM field of
the
EXEC statement is then available in the Linkage Section at the
location
specified as identifier-1. The first two bytes of identifier-1
contain a
count of the number of bytes of information in the PARM field; the
two bytes
are set to zero if the PARM field was omitted. This two-byte field is
binary
and should be defined with PIC S9(4) COMP. Immediately following
these two
bytes is the information in the PARM field. The maximum length of the
field
to be passed is 100 bytes.
...
Is this still in effect?
Does it specify, or does experiment show what happens if the program
is invoked (by LINK, ATTACH, CALL, XCTL, or address ATTCHMVS) with
a PARM>100 characters? Plausible actions:
o Runtime initialization terminates execution with an error indication.
This is as benign as JCL error.
o The PARM overlays adjacent data.
o Runtime initialization truncates the PARM. (I consider this
an integrity violation.)
o The identifier-1 is opaquely based on the content of GR1 at
program initiation. It is then the programmer's responsibility
to do his own truncation or overlaying.
Has anyone done the experiment?
There is nothing to experiment -- the 100 byte limit referred to is
from the JCL parm only. For that version of COBOL the limit on an
individual data item should have been 32K -- but those were the days of
BLL cells and managing your own based addressing -- parms could have
had some sort of practical limit of 4K.
However, if you passed MORE data into said program you would receive no
error, the COBOL program would only map the first 100 bytes or whatever
was defined. If you use the length to attempt a move that exceeded the
size of the item current versions of COBOL will abend with a U4038 and
a message that you attempted to reference an area outside of a defined
data item.
No truncation will occur.
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