At the Flying Pig downtown there were lockers under each bed that you had to lock, but I had a pretty expensive backpack and stuff and I never worried about it. I think there's a general coalition of backpackers in hostels to not touch eachother's shit. So I would leave mine on my room all day for the most part, and keep the more valuable stuff with me ( ie my camera ). But a lot of the hostels I went to there were rooms that you would put your stuff in and it would be locked all day and could only be locked with the key from the desk.
I wouldn't worry about it too much. I never once met someone who had there stuff stolen at a hostel...
I've been to 25 countries! Ask me where!
“Our battered suitcases were piled on the sidewalk again; we had longer ways to go. But no matter, the road is life.” – Jack Kerouac
"I set out alone, finding no companion to cheer the way with friendly intercourse, and no party of travellers with whom to associate myself. Swayed by an overmastering impulse within me, and a long-cherished desire to visit those glorious sanctuaries, I resolved to quit all my friends and tear myself away from my home."
---Ibn Battuta, CE 1325