IBM SC33-1683-02 - Manual (Page 174)

IC_ADDRE
is the address of an area containing the value of USERID.
Modifying fields in the command-level parameter structure
Some fields that are passed to interval control are used as input to the request,
some are used as output fields, and some are used for both input and output. The
method your user exit program uses to modify a field depends on the usage of the
field.
The following are always input fields:
INTERVAL
TIME
REQID
FROM
TERMID
SYSID
HOURS
MINUTES
SECONDS
USERID
The following are always output fields:
INTO
SET
The following are input fields on a START request and output fields on a
RETRIEVE request:
RTRANSID
RTERMID
QUEUE
LENGTH is an input field on a START request, an output field on a RETRIEVE with
SET specified, and an input/output field on a RETRIEVE with INTO specified.
Modifying input fields
The correct method of modifying an input field is to create a new copy of it, and to
change the address in the command-level parameter list to point to your new data.
Note: You must never modify an input field by altering the data that is pointed to by
the command-level parameter list. To do so would corrupt storage belonging
to the application program and would cause a failure when the program
attempted to reuse the field.
Modifying output fields
The technique described in “Modifying input fields” is not suitable for modifying
output fields. (The results would be returned to the new area instead of the
application’s area, and would be invisible to the application.)
interval control EXEC interface program exits
142 CICS TS for OS/390: CICS Customization Guide