KEVIN ZEMBOWER wrote:

The amanda man page says for the "use" parameter

  - a positive number means use only that amount
  - a zero means use all available
  - a negative number means use all EXCEPT that amount

You use parameter fits none of these exactly in that you have
a negative zero.  Is it possible the zero is being interpreted
as "all" and the negative as "except"?

You could leave it out too, and use the default ( = all space).