A program (e.g., an operating system) is provided a warning that it has a grace period in which to perform a function, such as cleanup (e.g., complete, stop and/or move a dispatchable unit). The program is being warned, in one example, that it is losing access to its shared resources. For instance, in a virtual environment, a guest program is warned that it is about to lose its central processing unit resources, and therefore, it is to perform a function, such as cleanup.