By default, TSO/E users are not notified when they have a transmission to receive. You can use exits to provide that information. Specifically, you can:

• Notify the sender of the original transmission that an acknowledgment is available to be received. Use the RECEIVE acknowledgment notification exit, or the RECEIVE termination exit, exit 13 in JES2, or IATUX42 in JES3.
• Notify the receiver that a file has arrived. Use exit 13, IATUX42, or the TRANSMIT termination exit.
• Prevent or force acknowledgment, using the TRANSMIT startup exit.
• Associate an acknowledgment with a specific transmission. The TRANSMIT startup exit can specify a notification string that gets passed with the transmission. If an acknowledgment is sent, the notification string is included in the acknowledgment transmission. The RECEIVE notification exit, which gets control each time an acknowledgment is received, can use the notification string to tie the transmission to the acknowledgment. The string is also passed to the RECEIVE acknowledgment notification exit.