* SQL (cursors): These statements contain the essence of the shared pool. In this chapter, I will provide details about cursors, but for now, think of a cursor as a chunk of memory connected to many other memory chunks containing information key to the proper functioning of the SQL statement.

* PL/SQL (cursors): These programmatic structures-such as functions, procedures, and packages-are also cached and therefore require shared pool memory. PL/SQL structures can consume a tremendous amount of shared pool memory.

* Library cache: This is used to locate objects in the shared pool and to ensure their proper relationship is maintained. While the library cache can be represented as a hashing structure (complete with buckets and chains), it is actually much more complicated than this. Efficient and unfettered library cache operations are central to a well-performing Oracle database system.