The Program Global Area (PGA) is a non-shared, writable memory area associated with a user process. Although the mechanism varies somewhat by operating system, the PGA is typically allocated when a server process establishes a connection to the instance via the SGA. There is a single PGA associated with each server process, and this area of memory is accessed only by Oracle code acting on behalf of this process.

The PGA always contains stack space for a session, which holds variables and other information associated with a session. The PGA may also contain session-specific information if the session is not established using the Multi-Threaded Server. If the Multi-Threaded Server is used, the session-specific information will be stored in the SGA.

The size of the PGA is determined automatically by Oracle and varies by operating system. The PGA size is affected by the following INIT.ORA parameters: