Large S7 tool steel bar stock should be kept clean, dry, and well-ventilated in order to maintain its quality. Moisture and humidity should be kept away from the steel because they might lead to rust and corrosion. Besides, it's essential to keep the steel away from any heat sources and open flames because heat can bend or deform the material. In order to avoid warping or bending, the steel should also be placed on a flat, level surface. Using rust inhibitors on the bar stock and wrapping it in corrosion-resistant materials like plastic or wax paper are other acceptable practices. It's also a good idea to regularly check the bar stock for any indications of corrosion or rust.