(1) A type of access control in which VSAM keeps control of the control interval (CI) containing a specific record until a REWRITE, UNLOCK, or DELETE command is issued for that record. The purpose of exclusive control is to protect against simultaneous update.
(2) A method for preventing multiple, write-add, basic direct access method (BDAM) requests from updating the same dummy record or writing over the same available space on a track. When specified by the user, the exclusive-control lock requests that the system prevent the data block that is about to be read from being modified by other requests; it is specified in a read macro and released in a write or read macro. When a write-add request is about to be processed, the system automatically obtains exclusive control of either the data set or the track.