Some libraries have closed stacks which are not open to the public, but most libraries are open stacks and allow their users to browse all or part of their stack areas. The open stacks movement revolutionized the purpose and role of libraries.
Library naming conventions can cause some user frustration between the word choice of "stacks" over "shelves" among those not familiar with the term. "Where are the stacks?" can be a common question at a reference desk.