Depends how early in the boot sequence you need the f/s.
RAMDISK is so last century, but it does have some (very specific) uses. Presuming you can mount after the kernel has loaded, look at using a tmpfs instead - you don't need to set it up or format a f/s; all handled in kernel cache. You can set a max size as well.
When the lxr site comes back online have a read of
this (or look in your kernel source tree if you have it).
Edit: you said "static sized" - I gave you a maximum size option. Is "static" an absolute requirement ?.
