Green’s Dictionary of Slang

big, excessive; thus staver n., someone or something exceptional.

1862		N.-Y. Trib. 7 Feb. 5/6: A staving dram put him in a better humor [DA].
1869		H.B. Stowe Oldtown Folks 117: She was spoken of with applause under such titles as ‘a staver,’ ‘a pealer,’ ‘a roarer to work’.
1876		F. Remington letter in Splete Sel. Letters (1988) 12: We’ve got a staving old Latin lesson today.
1884		(con. c.1840) ‘Mark Twain’ Huckleberry Finn 120: This one was a staving dream.
1898		F.B. Lloyd in Hudson Humor of the Old Deep South (1936) 197: I made a stavin, stirrin speech. It must of been a ring-tail dick nailer, for the crowd was all with me at the finish.
1904		G.D. Chase ‘Cape Cod Dialect’ in DN II:vi 428: staving, adj. & adv. Excellent, exceeding.