Transfering parallelism to sub-makes explicitly

[David Wuertele]

I want total control over all build command environments, including for
sub-makes, so I followed Paul Smith's advice (see
http://thread.gmane.org/gmane.comp.gnu.make.general/6507/focus=6508) with this
line at the head of my makefile:

  unexport $(.VARIABLES)

This works great for me, except for one situation:  I can't figure out how to
explicitly pass down my "-j N" values to submakes.  There doesn't seem to be a
single make variable which contains the value of "N".  I would like to do
something like this:

  unexport $(.VARIABLES)

  SOMEVARIABLE := # ????

  target:
          $(MAKE) -j $(SOMEVARIABLE) target

How do I set SOMEVARIABLE so that my sub-make gets the same "-j N" that the
top-level got?

(I'm aware that recursive blah blah harmful blah blah, but this is third-party
software I'm driving).

Thanks,
Dave