I've not seen this spelling before. It's handsome, and definitely favourable to
Jocelyn which I find a bit feeble.
Joscelin AmbroseJoscelin AndrewJoscelin CharlesJoscelin Emil - I'm surprised
Emil isn't more popular in English speaking countries.
Joscelin FrederickJoscelin IsidoreJoscelin TheodoreJoscelin ThomasJoscelin Virgil