Portability and migration - IBM - AS/400

CICS/400 includes facilities for:

  • Porting CICS application programs from other platforms
  • Release-to-release compatibility

Porting application programs
A CICS COBOL or C application program that meets the application programming interface requirements of CICS/400, when ported from another CICS system, will behave as it did on the original system.The following list summarizes the features of the CICS/400 API that may affect the portability of an application:

  • Basic Mapping Support (BMS) functions available with CICS/400
  • BMS macro source input is the only acceptable input for map generation.
  • AD/Cycle COBOL/400 and ILE C are the compilers supported for CICS/400 application development. The level of language supported by the COBOL/400 and ILE C compilers means that certain changes could be required to mainframe COBOL and C programs.
  • EXEC CICS commands must conform to the API defined for CICS/400.
  • Support is for the command-level application programming interface only. The macro-level interface is not supported.
  • File control emulates the VSAM access methods. BDAM and the DL/I database are not supported. CICS/400 does not support, and cannot be run within, a System/36™ or System/38™ emulated environment.
  • Terminal device support for application programs is provided for:
    – 5250 terminals
    – 3270 terminals and printers, including those supporting double-byte display and printing
    – 3151 ASCII terminals
    – SCS printers
    – Emulation of terminal support for 3270 Model 2 and Model 5 devices
  • CICS/400 provides for connectivity with other CICS products by using intersystem communication (ISC) facilities for handling the APPC communication protocol. The data may be held on the iSeries or any remote CICS system.

Release-to-release compatibility
Because of the addition of new facilities, objects created under previous releases need to be converted before being used under the current release. In order that you can maintain compatibility between installations at the current release level and installations at previous release levels, CICS/400 allows you to:

  • Convert CICS/400 objects created under previous releases to the current release(upward migration).
  • Create CICS/400 objects on the current release of CICS/400 to be compatible with the previous release (downward migration).Previous releases that are supported for migration purposes are the last release of the previous version and the previous release of the current version.

For example,you may have a development installation supporting production installations. You wish to migrate the development installation to the new CICS/400 release but maintain the production installations at a previous release. Resource-definition tables created on the development installation after migration to the new release are not directly transferable to the production installations. You need to use the SAVCICSGRP CL command for downward migration. The reverse is also true: resource definitions in use on the production installations must be converted to the new format (upward migration) after being transferred to the development installation. You do this using the INZCICS CL command or the CONVERT option of the STRCICS CL command.

The release-to-release capability of CICS/400 also allows you to create applications either for the current-release development installation or for distribution to the production installations using a supported previous release. You use the TGTRLS option of the CRTCICSC or CRTCICSCBL CL command. Applications created on a previous release are compatible with the new release.

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