How long can I stay in China if I quit my China job?

Right now I'm on a Z visa, my resident permit is valid for 4 more months. However I am thinking of quitting my job and leaving China. How long after I quit do I have to leave? The last thing I want to do is overstay, but I would like to visit some family and friends after I quit but before I am forced to go.

Am I allowed to stay for the full time of the resident permit even if I am not working?