Obtaining Time Zone Names by selecting all the rows from v$timezone_names : timezone_names « System Tables Data Dictionary « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. System Tables Data Dictionary
3. timezone_names

You have to be the system user.

SQL>
SQL> SELECT * FROM v$timezone_names;

TZNAME                                               TZABBREV
---------------------------------------------------- ---------------------------
Africa/Algiers                                       LMT
Africa/Algiers                                       PMT
Africa/Algiers                                       WET
Africa/Algiers                                       WEST
Africa/Algiers                                       CET
Africa/Algiers                                       CEST
Africa/Cairo                                         LMT
Africa/Cairo                                         EET
Africa/Cairo                                         EEST

...
...
...

You can use value in the TZABBREV column as your time zone setting.