camping
There is no organized camping in the area.
lodging
The refugio next to the parking lot do hot meals and will also try to get you to stay overnight. Be aware that sleeping can be a problem on this altitude.
backcountry
Putting up a tent is possible, but it might take a while to find a good spot among the rocks. Water is available by melting snow from the glacier or from the refugio. El Alto is the nearest place to stock up on food.