I like
Jocelyn a lot, but it always seems to shorten to
Joss, which I find horrifying. So if I used it, it would be as a mn.
That said, I'd never given it a thought as a male name! Though of course it could be. And perhaps even
Joss would be more acceptable on a guy. Not everyone could carry it off, so considerate parents would give him a less surprising mn like
Michael or
Craig so that he could have an escape clause.