DECLARE 

v_lock      NUMBER;
v_lockhandle varchar2(200);

-- extra declarations here --

BEGIN

-- LOCK --
 dbms_lock.allocate_unique('lock_proc1', v_lockhandle);
 v_lock := dbms_lock.request(v_lockhandle,dbms_lock.x_mode);

/*** Execute the rest of the 
procedure
here
***/

Commit;

-- RELEASE LOCK -- 
 v_lock := dbms_lock.release(v_lockhandle);

END;

CREATE PROCEDURE MY_PROC1 IS
v_lock      NUMBER;
v_lockhandle varchar2(200);

-- extra declarations here --

BEGIN

-- LOCK --
 dbms_lock.allocate_unique('lock_plp', v_lockhandle);
 v_lock := dbms_lock.request(v_lockhandle,dbms_lock.x_mode);

/*** Execute the rest of the 
procedure
here
***/

-- RELEASE LOCK -- 
 v_lock := dbms_lock.release(v_lockhandle);

END;

PROCEDURE MY_SCHEMA.MY_PROC1
On line:  102
PLS-00201: identifier 'DBMS_LOCK' must be declared

SELECT * FROM USER_SYS_PRIVS;

USERNAME	PRIVILEGE	ADMIN_OPTION

MY_SCHEMA	EXECUTE ANY PROCEDURE	NO
MY_SCHEMA	CREATE ANY INDEX	NO
MY_SCHEMA	UNLIMITED TABLESPACE	NO
MY_SCHEMA	SELECT ANY TABLE	NO
MY_SCHEMA	CREATE TABLE	        NO