Stacks Fitness provides 2 hours of free parking at The Hive Garage, just across Railroad Street.
All you have to do is:
1) Use your gym fob to scan into the garage before you pull a ticket
2) This ticket will entitle you to 2 hours free. (If you park longer than 2 hours, you'll only be charged for that overage.)
3) Scan ticket on your way out.