The user exit is passed the user ID that is executing the EXEC CICS® LINK command. If the request is to a remote system and the request is not already part of an existing logical unit of work in that system, the DPL request can be executed under the modified user ID at the remote system. The modified user ID does not need to be configured on the CICS system that is executing the DPL user exit. The user ID is sent to the request as already verified; that is, any setting for the OutboundUserids attribute in the Communication Definitions for the remote system is ignored, and the user ID is sent without a password. If the exit changes the field UE_Dpluserid to a null string, the request is sent with no security attributes. If the user ID is unchanged, the security attributes are sent as configured by the Communication Definitions for the remote system.
If further requests are made within the same unit of work to the same remote system, the same user ID is used for all requests to that system for the particular logical unit of work.