The OS basically has no mean to run a wiki on. It more depends on a webserver to reach it, sometimes a database in the backround (I'd prefer those that don't need one though) and a script language like php or perl etc.
Here you can check which might be most suitable for your needs and even compare them etc. very nice site:
WikiMatrix - Compare them all
EDIT: dokuwiki is small, fast, easy and you can set permissions and stuff.