An ACS installation exit routine can return a series of messages to the batch job, started task, or TSO/E user. To return messages, set the value in ACERWNMG equal to the number of messages you want returned and place the text of the messages in ACERWMSG. ACERWMSG can hold up to six messages that must be 110 bytes long. Pad messages with blanks if needed.

If your ACS installation exit routine invokes the ACS interface routine, then the ACS routine might have created messages by issuing the WRITE statement. The system retains those messages in ACERWMSG and sets ACERWNMG equal to the number of messages. The system has not written them yet. After the ACS installation exit routine ends, the messages will be written along with any messages that the ACS installation exit routine adds. Your routine should not overlay messages that are already in ACERWMSG.