WHEN can I RE-retire?

Ok, this is for Californians only. Hope someone knows. I have an app't with CALPERS in June, but really want to know this beforehand. I've researched online and called, and if no one here can answer my ?, guess I have to wait until June....My question is this - I retired from a CALPERS job in 2006. In 2009, I reinstated from retirement to accept a position at a community college (CALPERS)....now, less than a year later, there is a very good chance I will be getting laid off, if not this year, maybe next year and I refuse to deal with the stress on not knowing....so, do I have to be vested here at the college (I've looked in the union contract, it is vague) meaning I have to work 5 years, or due to the impending layoff, can I just apply to CALPERS to re-tire once again whenever I wish? Because if I can, I am leaving asap. The lack of the CA budget is wreaking havoc with colleges and the program I work in is on the chopping block..thanks