After determining that the user has entered a valid subcommand name, use the ATTACH macro instruction to pass control to the requested subcommand processor.

You should code your ATTACH macro to specify that subpool 78 is to be shared with lower-level tasks.

Depending upon the function and complexity of the command processor and the subcommand processor, you may need to specify the ESTAI operand on the ATTACH macro to provide an error handling routine that receives control if the subcommand processor abnormally terminates. For information on error handling, see Processing Abnormal Terminations. For information on the ATTACH macro instruction, see z/OS MVS Programming: Authorized Assembler Services Reference ALE-DYN.

Subcommand processors are similar to command processors in many ways, including syntax and the way they receive control. When your command processor attaches the subcommand processor, you must pass a pointer to a command processor parameter list.