[oracle@rac2 ~]$ ps -ef | grep tns
root         9     2  0 05:10 ?        00:00:00 [netns]
oracle    3468     1  0 05:13 ?        00:00:00 /u01/app/11.2.0/grid/bin/tnslsnr LISTENER -inherit
oracle    5301  3976  0 05:38 pts/1    00:00:00 grep tns
[oracle@rac2 ~]$ lsnrctl status LISTENER | grep -i TEST <-- no output
[oracle@rac2 ~]$

SQL> select name, open_mode from v$database;

NAME      OPEN_MODE
--------- --------------------
POCNDEV   READ WRITE

SQL>

SQL> exec dbms_service.CREATE_SERVICE(SERVICE_NAME=>'TEST', NETWORK_NAME=>'TEST');

PL/SQL procedure successfully completed.

SQL> exec dbms_service.START_SERVICE('TEST');

PL/SQL procedure successfully completed.

SQL>

[oracle@rac2 ~]$ . oraenv
ORACLE_SID = [POCNDEV] ? +ASM
The Oracle base remains unchanged with value /u01/app/oracle
[oracle@rac2 ~]$ lsnrctl status LISTENER | grep -i TEST
Service "TEST.rajasekhar.com" has 1 instance(s). <----
[oracle@rac2 ~]$

[oracle@rac2 ~]$ lsnrctl status LISTENER
..
..
Service "TEST.rajasekhar.com" has 1 instance(s).
  Instance "POCNDEV", status READY, has 1 handler(s) for this service...
The command completed successfully
[oracle@rac2 ~]$

[oracle@rac2 ~]$ cd /u01/app/oracle/product/11.2.0.4/db_1/network/admin/
[oracle@rac2 admin]$ cat tnsnames.ora | grep -i TEST
[oracle@rac2 admin]$

-- dbms_service.CREATE_SERVICE will not add TNS entry to tnsnames.ora file.