Lock Management services for your PL/SQL applications
Subprocedures:
ALLOCATE_UNIQUE Allocate a unique lock ID to a named lock. 
REQUEST Function
                Request a lock of a specific mode.
                            nl -> Null
                            ss -> Sub Shared
                            sx -> Sub eXclusive
                            s  -> Shared
                            ssx -> Shared Sub eXclusive
                            x  -> eXclusive
CONVERT Function
                Convert a lock from one mode to another. 
RELEASE Function
                Releases a lock. 
SLEEP           Put a procedure to sleep for a specific time.  
For full documentation of the packaged procedures above see the Oracle Manual:
"Oracle9i Supplied PL/SQL Packages and Types Reference"
or the book Oracle Built in Packages by Steven Feuerstein et al
See also DBMSLOCK.SQL package specification file.
Related Commands:
LOCK TABLE
pRelated Views:p
 V$LOCK
 V$_LOCK
 V$LOCKED_OBJECT
 V$LOCKS_WITH_COLLISIONS
 V$LOCK_ACTIVITY
 V$LOCK_ELEMENT 
p