Under normal circumstances, request handlers such as the default handler for static files will discard the request body when it is not needed by the request handler. As a result, filters such as mod_include are limited to making GET requests only when including other URLs as subrequests, even if the original request was a POST request, as the discarded request body is no longer available once filter processing is taking place.

When this directive has a value greater than zero, request handlers that would otherwise discard request bodies will instead set the request body aside for use by filters up to the maximum size specified. In the case of the mod_include filter, an attempt to POST a request to the static shtml file will cause any subrequests to be POST requests, instead of GET requests as before.

This feature makes it possible to break up complex web pages and web applications into small individual components, and combine the components and the surrounding web page structure together using mod_include. The components can take the form of CGI programs, scripted languages, or URLs reverse proxied into the URL space from another server using mod_proxy.

Note: Each request set aside has to be set aside in temporary RAM until the request is complete. As a result, care should be taken to ensure sufficient RAM is available on the server to support the intended load. Use of this directive should be limited to where needed on targeted parts of your URL space, and with the lowest possible value that is still big enough to hold a request body.

If the request size sent by the client exceeds the maximum size allocated by this directive, the server will return 413 Request Entity Too Large.