You can manage minimum stay in your hostel in 'Manage' tab / 'Online Portals'
1. Select the portal, on which you want to set a minimum stay.
2. Log in to your XML Settings
3. Choose the Synchronize bookmark.
4. Select the dates for which you want to set up the minimum stay (guests, who will want to make a reservations starting on one of the selected dates will have to stay at least these number of nights, which you enter)
5 Select rooms for which you want to set up the minimum stay
6. Thick the "Minimum Stay Through" option
7. Enter the number of nights
8. Choose "Synchronize Now"
Please remember, that HostelSystem synchronizes only with 'Standard Rate'. If you've set up also other rates, you'll have to set up minimum stay manually in your Booking.com backofice.