CallbackFunction (MQPTR)

Callback descriptor structure - CallbackFunction field

The callback function is invoked as a function call.

Use this field to specify a pointer to the callback function.

We must specify either CallbackFunction or CallbackName. If you specify both, the reason code MQRC_CALLBACK_ROUTINE_ERROR is returned.

If neither CallbackName nor CallbackFunction is set, the call fails with the reason code MQRC_CALLBACK_ROUTINE_ERROR.

This option is not supported in the following environment: Programming languages and compilers that do not support function-pointer references. In such situations, the call fails with the reason code MQRC_CALLBACK_ROUTINE_ERROR.

On z/OS, the function must expect to be called with OS linkage conventions. For example, in the C programming language, specify: 
#pragma linkage(MQCB_FUNCTION,OS)

This is an input field. The initial value of this field is a null pointer or null bytes.

Note: When using CICS with IBM WebSphere MQ Version 7.0.1, asynchronous consumption is supported if:

  • Apar PK66866 is applied to CICS TS 3.2
  • Apar PK89844 is applied to CICS TS 4.1

Parent topic: Fields for MQCBD