The virtual memory functions allow you to allocate, free, reallocate, lock, and unlock blocks of memory. The virtual memory functions are declared in the include file VMEMORY.H.
| Routine | Use |
| _vfree | Frees an allocated block of virtual memory |
| _vheapinit | Initializes the virtual memory manager |
| _vheapterm | Terminates the virtual memory manager |
| _vload | Loads an allocated block of virtual memory |
| _vlock | Locks an allocated block of virtual memory |
| _vlockcnt | Returns the number of locks held on a block of virtual memory |
| _vmalloc | Allocates a block of virtual memory |
| _vmsize | Returns the size of an allocated block of virtual memory |
| _vrealloc | Reallocates a block of virtual memory to a new size |
| _vunlock | Unlocks a locked block of virtual memory |
The _vheapinit function specifies how much DOS memory the virtual memory manager can use and whether it should use expanded memory, extended memory, or disk storage. You must call this function before calling any of the other virtual memory functions.
The _vmalloc function returns a handle of type _vmhnd_t, which is used to refer to a block of virtual memory.
The _vfree, _vrealloc, _vload, _vlock, _vunlock, _vlockcnt, and _vmsize functions work on blocks of virtual memory specified by handles of type _vmdhnd_t.
The _vheapterm function frees all the resources used by the virtual memory manager. You must call this function after you have finished using virtual memory.