Whenever we travel in the US, we stop our mail. This isn't getting mail sent to where we are going. It's having our mail held at the post office until a specific date. On that date, you can either pick it up or have all of it delivered to your home mailbox. This service keeps the mailbox from overflowing, giving criminals the idea that the home may be empty at that time. I wonder if you're confusing stopping the mail with mail stop.
I'm native to the US and I also have never heard of such a thing. Perhaps it's for people traveling for a much longer time period with no single destination. In general, if you go to a single location for a temporary stay, say six months, you can have your mail forwarded to that location for that time period. At least I think you can do a temporary forwarding.