There is a FEX contribution for shared matrices on a single host. It does, however, only share a single matrix at a time, which could get clumsy for your purposes.
Extending shared memory to DCS would present difficulties. One worker per host would have to be nominated to create the shared matrix on that host, and the "last" worker (or that initial worker) would have to be responsible for removing it; this would require coordination between the workers that is not currently present. Especially as new copies of the worker might get scheduled on the host before all of the "first round" had disappeared.
The implementation could possibly take advantage of the fact that ipcrm will not actually delete a shared memory segment until the last detach. Well, on Linux and OS-X at least; I've never been convinced that MS Windows really implements POSIX to that level.
I suspect the matter might present problems in MS Windows on 32 bit systems, problems attaching the segment to the exact same virtual address in each process. The same virtual address needs to be used because the memory pointers that MATLAB uses internally are absolute addresses (absolute relative to the virtual address space of the process, as opposed to being segment + offset style that can be relatively easily relocated.)
As best I can tell, MATLAB is not designed to be able to work with memory pools internally, not designed to be able to bundle symbol tables and descriptors of variables and actual memory blocks, all within a restricted memory range. The creation of variables entirely within a memory segment for later sharing could possibly take a lot of internal work... I don't know.
