how do you control the stock?

Answer 1

You have no control over the price of a stock. A stock price goes higher and lower based off the expectations buyers and sellers have for the company's future performance and thus the stock price reflects these expectations.

Answer 2

Inventory control systems maintain information about activities within firms that ensure the delivery of products to customers. The subsystems that perform these functions include sales, manufacturing, warehousing, ordering, and receiving. In different firms the activities associated with each of these areas may not be strictly contained within separate subsystems, but these functions must be performed in sequence in order to have a well-run inventory control system.... (continue reading at the link)

Answer 3

Stock takes reconcile the figure in your books to the actual stock held, but the practical aspects are things like restricting access, CCTV, Order authorisation and checking.