Not to change the subject too much off of UTSA, but at 29,000 students and 6671 beds, Texas State has a pretty substantial on campus student living population at 23%. Adding that to the abundance of close to campus apartments gives San Marcos a very dense student population. Texas A&M and Texas Tech also have very impressive on campus percentage rates.
http://www.thecb.state.tx.us/reports/PDF/1722.PDF