When my alcoholic mother wore stockings, which was almost every day back in the '40's, she usually kept them up with roll garters. When she wore a girdle however, it was always an open bottom and no panties so if she needed to piss "right now", all she had to do was spread her legs apart and piss.
My maternal granny wore open bottom girdles except she had lots of belly and cunt hair to show off. I watched her piss many a time and perhaps could even have fucked her if I had offered her a bribe of whisky.