vUsing larger sends for a given large transfer (record sizes) provides a higher application data rate and decreases CPU time. With the larger record size, the CPU has less processing to do because there are fewer application reads and writes to transfer the same amount of data.

vIf a value of *CALC is selected for maximum Systems Network Architecture (SNA) request/response unit (RU), the system selects an efficient size compatible with the frame size. The frame size is on the line description that you choose. Changing the RU size to a value other than *CALC may negate the performance feature.

vCompression with APPC should be used with caution and only for slower speed wide area network (WAN) environments. Many suggest that compression should be used with speeds 19.2 kbps and slower.

vIf you are doing tasks that include repetitive, small puts; better performance is achieved if you use ICF or CPI Communications.

See the following topics for a more complete discussion of APPC applications:

vPerformance considerations for Intersystem Communications Function

vPerformance considerations for Common Programming Interface communications

For information about AS/400 communications, see the Communications Configuration book.

For more information about CICS/400, see the CICS/400 Administration and Operations Guide .

Performance considerations for intersystem communications function

You can use intersystem communications function (ICF) to write application programs that you want to communicate with advanced program-to-program communications (APPC). ICF also provides program-to-device communications between the AS/400 system and hardware devices. You must determine which system is to send data first before you write the program. ICF data management handles the communication functions and the data for your program. In particular, ICF should be used to do tasks that include repetitive, small inputs.

To optimize ICF performance, consider the following:

vEliminate unused record formats.

vUse separate record formats instead of multipurpose record formats with option indicators.

vCode to use the same record format for repeated operations.

vSet the maximum program devices equal to 1.

vUse a nonshared file.

vUse a separate indicator area.

vThe use of the ICF keywords force data and confirm should be minimized.

vUse the Request to Send keyword only when necessary.

vUse the Invite Only keyword when soliciting input from multiple devices, otherwise use the Read keyword instead.

vIf using the Invite keyword to solicit from multiple program devices, follow it with a Read-from-invited operation, not a Read operation.

To create device descriptions to get your system set up for ICF, do the following:

1.Type the appropriate Create Device Description commands on the AS/400 command line and press F4.

2.Use the online help information to choose the parameter values.

3.Press Enter. The device description is created.

For more information about ICF, see

v“Application program interface (API) performance considerations” on page 17

vICF Programming

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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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