The "official" mileage (FWIW) threshold for a beverage service in Y is 250 miles, but of course "conditions" can "prohibit service" on flights of any length when they want them to. AA's verbiage for flights under 250 miles is "by request" though, and IME on short flights the FA's have generally either announced that it was by request or happily accepted requests. My bigger experience has been the elusive "turbulence" excuse not to do service; stage length has been more to-the-rule in my experience.