If you are taking xanax for anxiety or panic disorder you should not drink AT ALL. Aside from the obvious: "It may also slow both the heart rate and breathing, which can cause you to pass out or have difficulty breathing -- and may even lead to death."
As K-d out mentioned: with short acting Benzos after a night of abuse of you have a condition your rebound anxiety will be horrible. There was a point SWIM ended up in the ER twice thinking they were having a heart attack due to rebound anxiety.
Finally if you are going to drink and take xanax I would say NO amount is "safe" to take as your bodies tolerance to the drug and alcohol will be different then anyone else's. What I can say is be sure if you mix the combo to avoid anything which will increase your core body temp. No hot tubs, sauna, even hot bath or showers can be dangerous. I would recommend enjoying one or the other or both just not at the same time. That combination is very dangerous. I have seen first hand people slip into a coma from 1mg. (Half bar) and a few glasses of wine. I have also seen it amplify the underlying anxiety issue if abused and stopped long term (search grand mal seizure) what I can promise is if you mix the 2 be prepped to be reminded the next day what you did the night before. Hopefully by a friend and not a cop! Be safe.
