Your message user routine provides a mechanism for receiving messages from other members of your XCF group. When you join an XCF group, you must specify the address of a message user routine to be given control when another member sends you a message. You also can specify a message user routine when invoking the XCF Message Control service (IXCMSGC REQUEST=CALLEXIT). This topic presents the following information to help you code a message user routine:

• The environment in which it receives control
• The information it receives as input
• The actions it might perform
• Programming considerations to bear in mind