AMRF(Y) means you want to activate the action message retention facility and is the default. If you specify AMRF(N), AMRF is not active.
Unless you code otherwise in MPFLSTxx, AMRF retains in a buffer area all action messages, those messages with descriptor codes 1, 2, 3, and 11, and WTOR messages.
AMRF works as follows. When the operator has performed the action required by a message displayed on the screen, the system deletes the message, or the operator can use the CONTROL C command to delete the message. If AMRF is active, operators can remove action messages from the screen, then retrieve them in their entirety later by using the DISPLAY R command (see Displaying information about messages awaiting action).
In a sysplex, it is recommended that you use AMRF. The AMRF keyword has sysplex scope.