1) This word of Old English origin had the basic meaning of ‘foundation’, a place where something might stand.
c.1530 he knoweth that Richard Longbothome ... paid fyne for a myllstedyll or rode of land nigh where the said mill now standeth, Halifax. It was commonly used in connection with stacks of agricultural produce, referring to the foundation materials: 1614 one stadle of rye, Stockeld
1642 that they rake cleane ... the staddles of the stookes after-that they have given up the stookes, Elmswell. The inference in coal-mining contexts may be that the coal stacks were built up on some kind of framework or platform: 1699 the liberty of laying, stacking stadleing and carrying away coals, Goldthorpe.