Unix has a configurable limit on the number of processes, file descriptors and threads available per user. This functionality is aimed to prevent a user from consuming all of the resources on a machine. These limits are often set to a reasonably low level, as a general purpose user will not consume many of these objects at any one time.

Application servers like Universal Messaging may, if under considerable load, want to consume a large number of these resources. Each open connection to a client for example consumes a file descriptor, and application servers which can support tens of thousands of concurrent connections will thus require as many file descriptors. It is therefore important to increase these limits for Universal Messaging.