When should you use synchronous cross memory communication?

The use of synchronous cross memory communication to provide services to users can provide virtual storage constraint relief as well as improve the integrity of the service and its data. Consider using synchronous cross memory communication if you wish to:

Isolate the service and its data from the user of the service
Make the service available to multiple users without the need to store it in commonly addressable storage
Replace an existing service request block (SRB) routine to gain improved performance or simplify communication
Provide an authorized service to problem state programs

Synchronous cross memory communication enables you to provide services to many users without making the service available in commonly addressable storage. At the same time, you can isolate the service from the user, thus protecting it by having the service in its own address space.