In a multitasking, multiprocessing environment, resource serialization is the technique used to coordinate access to resources that are used by more than one program. When multiple users share data, a way to control access to that data is needed. Users that update data, for example, need exclusive access to that data; if several users tried to update the same data at the same time, the result would be a data integrity exposure – the possibility of incorrect or damaged data. In contrast, users who only read data can safely access the same data at the same time.

z/OS® provides multiple ways of providing serialized access to data on a single or multiple systems, but global resource serialization is a fundamental way for programs to get the control they need and ensure the integrity of resources in a multisystem environment.

Because global resource serialization is automatically part of your system and is present during z/OS initialization, it provides the application programming interfaces that are used by the applications on your system. This is true even in the presence of vendor products.