VMS Help CC, Messages, MIXVLAALLOCA  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Message        Declaring a variable length array in the same block
                as a call to __ALLOCA will cause the storage
                allocated by any __ALLOCA call to<fragment> previous
                call to __ALLOCA was at <where>.

 Description    Storage allocated for arrays of variable length have
                their storage deallocated when the block they are
                declared in exits.  Storage allocated by __ALLOCA is
                not normally deallocated until function exit.  Compaq
                C can not support both types of deallocation in the
                same block.  Therefore, when both a vla array and an
                __ALLOCA call appear in the same block, the storage
                for both will be deallocated with the block exits.

 User Action    Be aware of this.  If the storage allocated for
                __ALLOCA must remain allocated until function exit,
                move the __ALLOCA call outside the block declaring
                the vla array.