Green’s Dictionary of Slang

(US) very, excessively.

1848		‘Ned Buntline’ Mysteries and Miseries of N.Y. IV 19: I do believe he’s gone stark stavin’ demented!
1879		Eve. Chronicle (Virginia City) 10 June in M. Lewis Mining Frontier (1967) 202: Hardy set to work an’ got the jockeys blind, stavin’ drunk.
1882		P. Ludlow Nick Hardy 111: Well, you smoke, and I’ll study; I’ve got a staving long lesson.
1898		F.H. Smith Caleb West (1902) 214: He tuk her to them Leroy folks; They was stavin’ good to her.
1902		W.N. Harben Abner Daniel 91: He got blind, stavin’ drunk.
1904		G.D. Chase ‘Cape Cod Dialect’ in DN II:vi 428: staving, adj. & adv. Excellent, exceeding. ‘We had a staving good time.’.
1917		Van Loan ‘Playing Even with Obadiah’ in Old Man Curry 61: I figure he’s got a stavin’ good chance to come second – a stavin’ good chance.