My answer would be that due to the extremly high forclosures, many are renting. However, it is NOT a hot rental market since commuters are moving back to their working communities (bay area) due to the cost of gas. When adding the added gas and Air Conditioning bill to a Stockton rental, most are realizing that the commute is out of the picture (even if you account for the price of ACE). People don't move out to Stockton to rent. There is a reason why there is such a large number of empty homes: no renters to fill them!!
Would the local market support an increase demand in rentals? There is nothing fueling that right now-- no new job creations (higher unemployment then most vicinities) or other factors that I know of! However, if one is chasing the "American Dream" of affordable home ownership, Stockton is the place! Historic low deals!! I lost over 50% on my house alone!