large object minimum storage

Do large objects have to be at least 16K, plus 16K for the index, even if
the object is much smaller?

I have a bunch of large objects of widely varying size.  Most are quite
small, but a few are above the 8K limit, so I thought I might just store
them all as large objects.  But this was taking up far too much space, and
I noticed that the xinv* and xinx* files were all 16K, which is much more
than most of them need.

Is this a configuration parameter?  I didn't see anything in the
documentation.  (I am currently using 6.3.2 on Redhat linux 5.2.)

I've pretty much decided to use arrays instead of blobs, and put the
"overflow" in a separate table for the few objects that exceed the limit,
but if anyone has any better ideas, I'd love to hear them.

Thanks

Ken