SQL> show user
USER is "LGE2008DEV"
SQL> create context krishna_ctx using krishna_pkg;

Context created.

SQL> CREATE OR REPLACE PACKAGE KRISHNA_PKG AS
  2    PROCEDURE MyProcedure;
  3  END KRISHNA_PKG;
  4  /

Package created.

SQL> 
SQL> CREATE OR REPLACE package body krishna_pkg is
  2  procedure MyProcedure
  3  as
  4  begin
  5  
  6  dbms_session.set_context( 'KRISHNA_CTX', 'SURNAME','Test');
  7  
  8  end MyProcedure; 
  9  
 10  end krishna_pkg; 
 11  /

Package body created.

SQL> exec krishna_pkg.MyProcedure;

PL/SQL procedure successfully completed.

CONNECT TO SCHEMA SITLGE2008
Connected.
SQL> show user
USER is "SITLGE2008"
SQL> CREATE OR REPLACE PACKAGE KRISHNA_PKG AS
  2    PROCEDURE MyProcedure;
  3  END KRISHNA_PKG;
  4  /

Package created.

SQL> 
SQL> CREATE OR REPLACE package body krishna_pkg is
  2  procedure MyProcedure
  3  as
  4  begin
  5  
  6  dbms_session.set_context( 'KRISHNA_CTX', 'SURNAME','Test');
  7  
  8  end MyProcedure; 
  9  
 10  end krishna_pkg; 
 11  /

Package body created.

SQL> exec  krishna_pkg.MyProcedure;
BEGIN krishna_pkg.MyProcedure; END;

*
ERROR at line 1:
ORA-01031: insufficient privileges
ORA-06512: at "SYS.DBMS_SESSION", line 90
ORA-06512: at "SITLGE2008.KRISHNA_PKG", line 6
ORA-06512: at line 1


FROM SYS
=========
select * from dba_context where namespace='KRISHNA_CTX'
"NAMESPACE"                    "SCHEMA"                       "PACKAGE"                      "TYPE"                 
KRISHNA_CTX                    LGE2008DEV                     KRISHNA_PKG                    ACCESSED GLOBALLY