The Lockheed TriStar is unique amoung jet transport aircraft, in that the entire horizontal tailplane is moved when 'elevator' forces are applied, for pitch change.
In addition, the stabilizer trim, like on other jet transports, is trimmed, to relieve control forces.
The TriStar does have an elevator, however its movement is linked directly to the stabilizer (ie: no separate movement possible by the pilot) to provide enhanced authority.
This feature, combined with DLC
(direct lift control, ie: spoilers for pitch assist, after landing flaps are selected), provides a very stable and constant body angle for automatic landings.