With the XCF Message Out service, the sender can specify a timeout value after which the message is to be considered complete. The timeout value is the number of seconds the sender is willing to allow for the message-out request to complete. XCF declares the message to be complete if it does not otherwise complete during the timeout interval. The sender is notified of the message completion in the manner requested when the message was sent. The system discards any response that is received after the message is considered complete.

A nonzero timeout value is required when MSGACCESS=ASYNC is specified on the Message Out service. Users sending large messages should allow sufficient time for the message to be sent. As a general rule, allow at least one millisecond per 4K of message data for data transfer time. Multiply the value by the number of targets and add additional time for system delays, such as spin loops, dumps, or response collection.

Consider also the rate at which the member processes its messages and the size of the messages. If a large number of messages arrive at a rate greater than the system's ability to process them, the system might need large amounts of storage to maintain the backlog. If a broadcast with response to a large number of target members requires a large response from each member, the system might need large amounts of storage to maintain the responses. Although XCF uses pageable data spaces to manage the message traffic, your application must be aware of the system resource impact to the system and the sysplex.