Returning from a Called Program

or

Procedure

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Multiple

PLISTs

can

appear

in

a

procedure.

However,

only

one

*ENTRY

PLIST

be

specified,

and

only

in the

 

main

procedure.

 

 

 

 

 

 

 

 

 

 

For

examples

of

 

the

 

PLIST

operation

see

Figure 47

on

page 105

and

Figure

on page 239.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Returning from a Called

 

Program

 

or

Procedure

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

When

a

program

or procedure

returns, its

call

stack

entry

 

is

removed

stack.

(If

it

 

is

a

program,

the

program

entry

procedure

 

is

removed

dure

ends

abnormally

 

when

something outside

the

procedure

ends

its

invo

For example, this would occur if an

ILE

RPG procedure

X

calls

another

(such

as

a

CL

procedure) that issues an escape message

directly

to

calling

X.

This

would

also

occur

if

the

procedure

gets

an

exception t

by

an

 

exception

handler

(a

*PSSR

or

error

indicator)

of

a

 

procedure

call

stack.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Because of the cycle code associated with main procedures, their r associated with certain termination routines. This section discusses the ways that main procedures and subprocedures can return, and the actio occur with each.

Returning from a Main Procedure

A return from a main procedure causes the following to occur:

¹ If LR is on, files are closed and other resources are freed.

¹ The procedure's call stack entry is removed from the call stack.

¹If the procedure was called by the program entry procedure, the

entry procedure is also removed from the call stack.

A main procedure returns control to the calling procedure in one of th ways:

¹ With a normal end

¹ With an abnormal end

¹ Without an end.

A description of the ways to return from a called main procedure foll

For

a

detailed

description

of where

the

LR, H1

through

H9,

and RT i

tested

in the

RPG

program

cycle, see

the

section

on the

RPG

program

ILE

RPG

for AS/400

Reference.

 

 

 

 

 

Normal End

A main

procedure ends normally and control returns to the calling procedu

the LR

indicator

is on and the H1 through H9 indicators are not on.

cator

can be set

on:

¹implicitly, as when the last record is processed from a primary or

during the RPG program cycle

¹ explicitly, as when you set LR on.

A main procedure also ends normally if:

152 ILE RPG for AS/400 Programmer's Guide

Page 175 Page 177
Page 176
Image 176
IBM AS/400 manual Returning from a Main Procedure, Normal End, Returning from a Called
Page 175 Page 177

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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