Users use the TRANSMIT command to send information (a message) or a copy of information (a data set), or both, to another user. Users use the RECEIVE command to retrieve the data. For information about setting up the TRANSMIT and RECEIVE environment, see Setting up the TRANSMIT and RECEIVE environment.

If RACF® is installed, and if your installation has activated security label checking, data sets and messages have security labels (SECLABELs) associated with them. The security label of the transmitted information is checked with the security label of the receiving user's current logon session. The result of that check determines if the receiving user is authorized to receive the data set or message. If the check determines the receiving user is authorized for the proper security label, but is not currently logged on at the proper security label, the data set or message will not be deleted. If the check determines the receiving user is not authorized for the proper security label, then the data set or message may be deleted. However, your installation can set up a JES exit to hold or reroute data sets that would otherwise be deleted.

For more information about setting up security labels, see .

Several TSO/E exits enable your installation to modify the way TRANSMIT and RECEIVE operations are performed, or to monitor or restrict transmission activity. The TSO/E exits are described in this chapter.