If the sender of data requested acknowledgment, the RECEIVE pre-acknowledgment notification exit (INMRZ06R) receives control before the acknowledgment is sent. The exit enables installations to suppress acknowledgments and alter sending and receiving userid/node pairs. If the SECLABELs of the sender and receiver are different, the installation can specify which SECLABEL to use to send the acknowledgment.

If RECEIVE is processing several files, each with an acknowledgment, this exit is invoked multiple times during RECEIVE processing.