I think only the moderators can mark a topic as stickied. It’s listed in the moderators’ “Thread Options,” which any user can view at the bottom of any thread, so I”d suppose that it’s a moderator’s duty. I’ve never been clear on that, however. If a topic is truly important and you directly ask the moderators to sticky it, I’m sure one of them will do that for you.

The moderators can probably answer this question much better than I can, given that I know most of what I know about this site’s workings simply from observing their conduct. I think they understand their conduct better than I do.

Peace
The Man