Delay Type

Reason

Data set in use by another application

When jobs are executed concurrently, z/OS provides data integrity by using system-wide enqueues.

If a job allocates a data set by using DISP=SHR, it has concurrent access, but each program must ensure data integrity. If a job allocates a data set by using DISP=OLD, the z/OS operating system provides data integrity and requires all other programs to wait until the data set is free.

Reduce resource conflicts by ensuring that jobs use the same resources in a serial manner.

Logical resources in use by another application

z/OS provides the ENQUEUE/DEQUEUE facility to ensure that logical resources are protected when multiple jobs or tasks require serialization.

For example, when the program uses the ENQUEUE facility to provide a queueing function for a server task, the requesting tasks waiting in ENQUEUE are delayed.

Reduce resource conflicts, caused when queueing is emulated with the ENQ/DEQ services, by using another queueing algorithm.