gtpd1m3bDatabase Reference

Coupling Facility Locking Functions

This section will help you to understand how to use the serialized list structure as well as provide information about the CF locking functions and the format of the CF lock.

Overview

As discussed previously in Coupling Facility List Structure, a serialized list structure is a list structure that contains a lock table. The lock table is an array of exclusive locks whose purpose and scope are defined by the application. Lock table locks can provide a serialization mechanism for lists, list entries, or any other list structure entity you designate. The first connector to a CF list structure specifies whether it is to be a serialized list structure and, if so, the number of lock entries to be allocated in the lock table. Figure 60 shows a serialized list structure.

Coupling Facility Lock Format

The CF lock is used to serialize operations on the CF and is 16 bytes long. Figure 66 shows the format of the CF lock.

Figure 66. Format of the CF Lock


In the CF lock:

The following scenarios illustrate how the content of the CF lock changes when different CF operations are performed or various system states occur.