Overview

The master subsystem synchronizes resource requests to the Beta product subsystem. It locks a resource when a batch job or subsystem is given access to this resource and places all other requests for this resource in a waiting list. After the resource becomes free, the batch job or subsystem which is next in the queue is given control.

Resource locking can take place on three different levels:

• The whole database can be locked (master lock).
• A single file can be locked (file lock).
• Other resources like tables and pools can be locked.

All serialization takes place in the address space of the master subsystem. If a requesting subsystem or batch job abends abnormally, the obsolete requests are deleted from the waiting list by the master subsystem. If a subsystem or batch job abends while it has control over a resource, the resource is unlocked by the master subsystem.