Lil Za -- I Didn't Go Running To Mommy, Still Living Large At Justin Bieber's

Lil Za and Justin Bieber are still roomies --- TMZ has learned Za is NOT moving out ... and is NOT being forced out of Bieber's Calabasas home ... despite his arrest for drug possession.

There was speculation Bieber ordered Za to pack his bags and move out ... after Za was spotted at a hotel near JB's house immediately after the arrest.

But sources close to Za tell us he was only visiting his mom, who flew in from Texas following his drug bust -- and chose to crash at a hotel instead of Beiber's pad.

Za's girlfriend -- Atifa Barwany -- also came out from Texas. She's the chick who's been tooling around Bieber's house on Segways with Za.

A man's home is someone else's castle.