Program/Procedure Call Overview

¹Recursion

¹Parameter passing considerations

Calling Programs

You

can

call

OPM

or ILE

programs by

using

program callcalls. isA

a

 

 

 

 

call that is made to a

program object (*PGM). The

called

program's

name

resolved

to

an

 

address

at run time, just before the calling

program

p

to

the

called program for the first time. For this reason, program ca

referred to as dynamic calls.

 

 

 

 

 

 

 

 

 

 

 

 

 

Calls

to

an ILE

program,

an

EPM

program,

or

an

OPM

program

are all

example

program

calls.

A

call

to

a non-bindable API

is also

an

example

of

a

pro

You

use

the

 

CALLP operation

or

both

the

CALL

and

PARM

operations

 

to

make

program

call. If you use the

CALL

and

PARM

operations,

then

the

compiler

perform

type

 

checking

on

the

parameters,

which

may

result

in

run-time

e

When an ILE program is called, the program entry procedure receives t parameters and is given initial control for the program. In addition, a within the program become available for procedure calls.

Calling Procedures

Unlike OPM programs, ILE programs are not limited to using program calls. programs can also use static procedure calls or procedure pointer call

procedures.

Procedure

calls are also

referred

to

as

bound

calls.

A

static

procedure

call

is

a

call to an ILE procedure where the name of

dure

is

resolved

to

an

address during binding — hence, the term stat

run-time performance using

static procedure calls is faster than run-time

ance

using program

calls. Static calls allow operational descriptors, omitt

eters,

and

they

extend

the

limit

(to

399)

on

the

number

of

parameter

passed.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Procedure

pointer

calls

provide

a

way to call a procedure dynamically. For

example,

you

can

pass

a

procedure pointer as a parameter to another

which

would

then

run the

procedure

that

is

specified

in

the

passed

can also

manipulate arrays

of

procedure

names

or

addresses

to

dynamic

a

procedure

call

to different procedures. If the called procedure

vation

group,

the

cost

of

a

procedure

pointer

call

is

almost

identical

static

procedure

call.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Using either type of procedure call, you can call:

¹A procedure in a separate module within the same ILE program or se program.

¹ A procedure in a separate ILE service program.

Any procedure that can be called by using a static procedure call c called through a procedure pointer.

For

a list of examples using

static

procedure

calls, see “Examples of

Call”

on page 135 and “Examples

of CALL

and CALLB”

on page 150. For exam-

128 ILE RPG for AS/400 Programmer's Guide

Page 151 Page 153
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IBM AS/400 manual Calling Programs, Calling Procedures, Static
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AS/400 specifications

The IBM AS/400, now known as the IBM iSeries, is a midrange computer system that has been a cornerstone of enterprise computing since its introduction in 1988. Designed to provide a robust platform for business applications, the AS/400 is celebrated for its reliability, scalability, and integrated database capabilities.

One of the key features of the AS/400 is its Integrated Operating Environment, which blends hardware and software resources seamlessly. This integration allows businesses to execute diverse workloads, ranging from traditional applications to modern web-based services, all on a single platform. The operating system, OS/400 (now IBM i), offers a rich set of APIs and tools for developers, simplifying application development and management.

Another standout characteristic of the AS/400 is its built-in database, DB2 for i. This powerful relational database management system allows for efficient data handling and provides advanced features such as support for SQL, XML, and JSON, making it easier for businesses to manage their data and integrate it with other systems. The database's tight integration with the operating system enables high performance and security.

In terms of scalability, the AS/400 can accommodate small businesses as well as large enterprises, with the ability to support hundreds of users simultaneously. Its architecture allows for easy upgrades in hardware, meaning that organizations can scale their systems without replacing the entire infrastructure.

Security is another critical attribute of the AS/400. With a sophisticated security model, it offers built-in user authentication, access control, encryption, and auditing capabilities to protect data and applications from unauthorized access.

The AS/400 also supports multiple programming languages, including RPG, COBOL, Java, and PHP, giving organizations the flexibility to choose the development tools that best fit their needs. This diversity helps maintain legacy applications while also developing new ones that leverage modern technologies.

Moreover, the platform supports both traditional green-screen interfaces and modern graphical user interfaces, allowing organizations to transition smoothly into contemporary user experience paradigms.

Overall, the IBM AS/400 stands out as a resilient, flexible, and secure computing platform that enables organizations to effectively manage their business operations, streamline processes, and adapt to changing market demands. Its unique combination of integrated features and capabilities ensures that it remains relevant in today's fast-paced technology landscape.
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