Internet Information Server runs in a pageable user-mode process called Inetinfo.exe. The HTTP, FTP, and Gopher services run in the Inetinfo process and share the threads of the process. The working set of the Inetinfo process is the space in physical memory visible to the Inetinfo process.
Internet Information Server stores its code and frequently used data in the Inetinfo working set. For Internet Information Server to run efficiently, it must be able to maintain all of its code and the most frequently used files in its working set. In addition, the working set of the Inetinfo process should be large enough to contain the IIS Object Cache, data buffers for IIS Logging, and the data structures HTTP uses to track its active connections.
There is no fixed optimal size for the Inetinfo working set. The requirements of the working set vary depending upon the number of connections maintained, the number and size of files, and the use of other supporting services, such as security features and logging.
You can monitor the Internet Information Server process as it runs on your server to determine whether its working set is large enough to support the IIS services.