Managing Dynamically-Allocated Storage

Note: Although the ALLOC operation code works only with the default heap REALLOC and DEALLOC operation codes work with both the default heap and user-created heaps.

Figure 52

shows

an

example

of how the

memory management operation codes

can be

used

to

build

a

linked

list

of names.

 

 

 

 

 

 

 

 

 

 

 

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

* Prototypes for subprocedures in this module

*

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

D AddName

 

PR

 

 

 

 

 

 

D

name_parm

 

 

 

40A

 

 

 

 

D Display

 

PR

 

 

 

 

 

 

D Free

 

PR

 

 

 

 

 

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

* Each element in the list contains a pointer to the

*

 

* name and a pointer to the next element

 

*

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

D elem

 

DS

 

 

BASED(elem@)

 

 

D

name@

 

 

 

*

 

 

 

 

D

next@

 

 

 

*

 

 

 

 

D

name_len

 

 

 

5U 0

 

 

 

 

D nameVal

 

S

 

40A

BASED(name@)

 

 

D elemSize

 

C

 

 

%SIZE(elem)

 

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

* The first element in the list is in static storage.

*

 

* The name field of this element is not set to a value.

*

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

D first

 

DS

 

 

 

 

 

 

D

 

 

 

 

*

INZ(*NULL)

 

 

D

 

 

 

 

*

INZ(*NULL)

 

 

D

 

 

 

 

5U 0 INZ(0)

 

 

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

* This is the pointer to the current element.

*

 

* When elem@ is set to the address of <first>, the list is

*

 

* empty.

 

 

 

 

 

 

*

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

D elem@

 

S

 

*

INZ(%ADDR(first))

 

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

* Put 5 elements in the list

 

 

 

*

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

C

 

 

DO

 

5

 

 

 

 

C

'Name?'

 

DSPLY

 

 

name

40

 

C

 

 

CALLP

 

AddName(name)

 

 

 

C

 

 

ENDDO

 

 

 

 

 

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

* Display the list and then free it.

 

 

*

 

*-----------------------------------------------------------------

 

 

 

 

 

 

*

 

C

 

 

CALLP

 

Display

 

 

 

 

C

 

 

CALLP

 

Free

 

 

 

 

C

 

 

EVAL

 

*INLR = '1'

 

 

 

 

 

 

 

 

Figure 52 (Part

1

of 5).

Memory Management - Build a Linked List of Names

114 ILE RPG for AS/400 Programmer's Guide

Page 137 Page 139
Page 138
Image 138
IBM AS/400 manual Managing Dynamically-Allocated Storage, Inz*Null, Dsply
Page 137 Page 139

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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