n. — especially Ontario
a small store selling snacks and miscellaneous items, often inside a hospital or school.
Type: 2. Preservation — The term appears to have been preserved from British English (see OED-3, s.v. "tuck shop"). However, in British English, tuck shop usually refers specifically to a sweet shop for children and youth. In the Canadian context, the meaning has been generalized to include any small shop that sells snacks; however, South African English (see Chart 1, .za) employs the term most frequently and most diversely. As Chart 2 shows, within Canada the term is centred in Ontario (like other terms, such as cube van.
See also COD-2, s.v. "tuck shop" (1), which is marked "Cdn"; in light of Chart 1, it is a Commonwealth term that can only be considered Canadian in relation to low use in the US.
See also: cube van
Images:

Chart 1: Internet Domain Search, 12 Oct. 2012 
Chart 2: Regional Domain Search, 19 Jul. 2016