ACL fills following fields when ACL RETURN to ALST:

ACL-RETCODE

The return code (0 is success; -1 is failure).

ACL-RETMSG

If ACL-RETCODE=0, ACL-RETMSG contains initial input string that denotes how to call a transaction (the input string is the exact input that user types in 3270 terminal instead of the real 3270 data stream. ART for CICS will compose the 3270 data stream from the input string). The size of this field is 1920 bytes (padded with trailing spaces if needed).

ACL-MSGLEN

Length of the initial input string ACL-RETMSG.

If the value is zero, ART for CICS removes trailing spaces/binary zero from ACL-RETMSG.

If the value is non-zero, this value should be the size of the message (a positive integer less than or equal to 1920), and then ART for CICS uses this size to call the transaction.

FILLER

Reserved 60 characters for future use. It must be binary zeros.