A lock is the mechanism that controls access to data pages and tablespaces.
The three types of locks are shared, update and exclusive.
DB2 imposes locks of four differing sizes: pages, tables, tablespace and for indexes subpage.
Attribute of Locks
Object : How much data is marked ?in-use?
Duration : How long is the lock needed (The lock duration are the lengths of time a lock is held. )
Mode : How severe is the lock ( The type of access allowed for the lock owner as well as the type of access permitted for concurrent users of the locked object. )