IMS compatible mode considerations

The following shows how AR/CTL supports IMS compatible mode environments, where AR/CTL replaces IMS.

AR/CTL product license

You must have a CPU authorization password to enable AR/CTL for IMS.

IMS requirements

If you are using AR/CTL for IMS in IMS compatible mode, no IMS license is required. In IMS compatible mode, AR/CTL uses no IMS code.

IMS calls

The application program cannot issue any other types of IMS calls except for checkpoint (CHKP), extended restart (XRST), and GSAM-type calls. The program cannot access any full-function IMS databases.

Generated control blocks

The application program can continue to use existing DBDs and PSBs that are generated by IMS utilities. AR/CTL does not provide utilities to generate these control blocks. If you no longer have the IMS utilities for control block generation and you need to change or create a control block for an application program, you must replace all IMS format control blocks with AR/CTL-format control blocks.

IMS region types

The application program JCL must be set up to execute a DLI batch region. Batch message processing (BMP) regions are not supported for IMS compatible mode.

Automatic restart and automatic checkpoints options

For IMS compatible mode programs, AR/CTL does not support the Automatic Restart option or the Automatic Checkpoints option.