Method to Provide Latch Options
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2005-Feb-15
A method is described to provide an efficient latch capability that avoids x-latch starvation using assembler language. The general approach is to use in-line assembler code, using an access latch approach as described in [*]. Once the access latch is held, the appropriate status flags in the latch area are checked and/or set. The sqloulat (latchptr) resets the latch ownership, adjusting count/status as required. It should be noted that: . Instant latches do not cause control block changes and are honored (if possible) even if an x-latch request is waiting to be honored. . If a conditional request is made which cannot be honored, control is returned to the calling process and a NOT_AVAILABLE return code is passed back. .