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Using the Fixed-Form Call Operations
2. Optionally code an error indicator (positions 73 and 74) or an LR indicator
(positions 75 and 76) or both.
When a called object ends in error the error indicator, if specified, is set on.
Similarly, if the called object returns with LR on, the LR indicator, if specified, is
set on.
3. To pass parameters to the called object, either specify a PLIST in the Result
field of the call operation or follow the call operation immediately by PARM
operations.
Either operation transfers control from the calling to the called object. After the
called object is run, control returns to the first operation that can be processed after
the call operation in the calling program or procedure.
The following considerations apply to either call operation:
The Factor 2 entry can be a variable, literal, or named constant. Note that the
entry is case-sensitive.
For CALL only: The Factor 2 entry can be
library name/program name
, for
example, MYLIB/PGM1. If no library name is specified, then the library list is
used to find the program. The name of the called program can be provided at
run time by specifying a character variable in the Factor 2 entry.
For CALLB only: To make a procedure pointer call you specify the name of
the procedure pointer which contains the address of the procedure to be called.
A procedure can contain multiple calls to the same object with the same or
different PLISTs specified.
When an ILE RPG procedure (including a program entry procedure) is first
called, the fields are initialized and the procedure is given control. On subse-
quent calls to the same procedure, if it did not end on the previous call, then all
fields, indicators, and files in the called procedure are the same as they were
when it returned on the preceding call.
The system records the names of all programs called within an RPG procedure.
When an RPG procedure is bound into a program (*PGM) you can query these
names using DSPPGMREF, although you cannot tell which procedure or
module is doing the call.
If you call a program using a variable, you will see an entry with the name
*VARIABLE (and no library name).
For a module, you can query the names of procedures called using DSPMOD
DETAIL(*IMPORT). Some procedures on this list will be system procedures; the
names of these will usually begin with underscores or contain blanks and you
do not have to be concerned with these.
For CALLB only: The compiler creates an operational descriptor indicating the
number of parameters passed on the CALLB operation and places this value in
the *PARMS field of the called procedure's program status data structure. This
number includes any parameters which are designated as omitted (*OMIT on
the PARM operation).
If the (D) operation extender is used with the CALLB operation the compiler
also creates an operational descriptor for each character and graphic field and
subfield.
Chapter 10. Calling Programs and Procedures 149