IMO, as I have explained in the specific thread about this question the most accurate term would be Static Corps and for the reasons pointed in that thread. A Regiment sized or even a Battalion sized unit could be considered garrisons of a city, sea port, air base, etc. But when we refer to larger territories to cover then we should use another name instead of garrisons. German Hoheres Kommandos were corps sized units with a territorial role so they did not have offensive capabilities nor motorised equipment: that´s why the reduced movement. These german units would pretty match with the concept of Static Corps. The same could be said for Wehrkreiskommandos or the american Service Command Corps.
This question could have more importance depending on the new amphibious rules will allow or not the garrison units to land anywhere but only in friendly sea ports.
