When I closed down Tallahatchie Woodworks, I found myself with about 5,000 primo wood shafts. I stored them simply laid on their sides in loose plastic bags on a wide shelf in an unheated storage building, sorted by spine and length so I knew what was what, and they stayed that way for more than 10 years before I did something with them. The only deterioration was some darkening on the top layer where the sun got to them through a window. They maintained straightness well, and were as good as the day they were made, maybe better from the stress relief from the long-term storage.
I wouldn't bundle them in any way that puts stress on the wood.