Call Procedure in OAF (1 input, 1 output parameter)

String sql = "BEGIN xx_custom_pkg.custom_prc (:1,:2); END;";
            try {
                OracleCallableStatement cs =
                    (OracleCallableStatement)oam.getOADBTransaction().createCallableStatement(sql,
                                                                                              2);
                ((OracleCallableStatement)cs.registerOutParameter(2,
                                                                  Types.VARCHAR,
                                                                  0, 2000));
                cs.setString(1, xxAttribute1Value);
                cs.execute();
                String outParamValue = cs.getString(1);
                pageContext.writeDiagnostics(this,
                                             "Result is:" + outParamValue,
                                             OAFwkConstants.PROCEDURE);
                cs.close();
            } catch (Exception ex) {
                pageContext.writeDiagnostics(this, "Error:" + ex.toString(),
                                             OAFwkConstants.PROCEDURE);
            }