Library stack

In library science and architecture, a stack or bookstack (often referred to as a library building's stacks) is a book storage area, as opposed to a reading area. More specifically, this term refers to a narrow-aisled, multilevel system of iron or steel shelving that evolved in the nineteenth century to meet increasing demands for storage space. An "open-stack" library allows its patrons to enter the stacks to browse for themselves; "closed stacks" means library staff retrieve books for patrons on request.