Abstract: In a sheet stacking apparatus, especially a recirculating document handler for recirculating document sheets for precollation copying at a copier platen to and from a stack in a document tray without obstructing access to the document tray, with restacking edge guides repositionable to accommodate stacking different sheet sizes and a restacking feeder for restacking the document sheets in the tray within the restacking edge guides by feeding each document in over the top of the stack from one edge and releasing the document to restack, there is provided automatically varying corrugation restacking apparatus enabling controlled restacking for recirculative copying of large flimsy documents such as Japanese B4 size sheets compatibly with normal document sizes having sheet corrugating members repositioned by movement of a repositionable restacking edge guide into a position to restack such large sheets and automatically providing in coordination therewith additional sheet corrugation in response to the flimsines