Freeing Virtual Memory

The VirtualFree function performs one of the following operations:

• Decommits one or more committed pages, changing the state of the pages to reserved. Decommitting pages releases the physical storage associated with the pages, making it available to be allocated by any process. Any block of committed pages can be decommitted.
• Releases a block of one or more reserved pages, changing the state of the pages to free. Releasing a block of pages makes the range of reserved addresses available to be allocated by the process. Reserved pages can be released only by freeing the entire block that was initially reserved by VirtualAlloc.
• Decommits and releases a block of one or more committed pages simultaneously, changing the state of the pages to free. The specified block must include the entire block initially reserved by VirtualAlloc, and all of the pages must be currently committed.