I carry mine in the pack, trying to keep it out of the sun so that my food is not supper heated during the day. At night I place it where i can see it 20-30 feet form my tent. Think about where it can roll to if a bear "plays" with it.
NPS website says,
"the bear canister only works if it's closed and locked! Be sure to keep it closed and locked, even while you're around your campsite. Place the canister on the ground in a flat, level area
100 feet or more from your campsite. Take care not to place it near a cliff or any water source, as a bear may knock the canister around or roll it down a hill. Do not hang or attach anything to the canister (ropes attached to the canister enable a bear to carry the it away). You can place pots and pans on top of the canister as a bear alarm if you like."
part of the idea is to significantly separate the THREE areas: food cooking area, food storage area, and sleeping area, for the benefit and safety of the humans by reducing potential for close encounters.