At many installations, users must share access to data in a data space. Users who are updating data for common use by other programs need exclusive access to that data during the updating operation. If several users tried to update the same data at the same time, the result would be incorrect or damaged data. To protect the integrity of the data, you might need to serialize access to the data in the data space.

Serializing the use of the storage in a data space requires methods like those you would use to serialize the use of virtual storage in an address space. Use the ENQ and DEQ macros, compare and swap operations, or establish your own protocol for serializing data space use.