Using different serialization techniques for the same volume

A task interlock can occur within a global resource serialization complex when two tasks reserve the same volume and some of the RESERVEs specify resource names that suppress the hardware reserve while other RESERVEs are hardware reserves that lock up the entire volume. The UCB count of outstanding reserves for that volume is manipulated only for the hardware RESERVEs.

If you code a RESERVE macro, the hardware reserve is suppressed when the resource name appears in the reserve conversion resource name list (RNL). See z/OS MVS Planning: Global Resource Serialization for additional information about RNLs and about preventing interlocks.