Green’s Dictionary of Slang

1. any form of performance venue.

1939		Goodman & Kolodin Kingdom of Swing 184: The worst thing [. . .] was that we only played for the dinner session. The room closed about 10:30 or 11 o’clock .
1956		B. Goodman ‘That Old Gang of Mine’ in Collier’s 20 Jan. 26: The Congress was known as a dead room; nobody had ever done much business in it.
1971		B. Short Black and White Baby 181: At MCA one of the agents said yes, he had a spot for us, not too much money, but one of the best rooms in town .

2. (N.Z. prison) a cell, thus the excl. room service! when an inmate wishes to make a request of an officer.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 155/2: room n. a cell [...] room service! a call to attract attention from a prison officer whenever an inmate wants something in his cell.