To connect the memory area for use by a 'file':
with LUN: stream number
MBUF: user memory of NWBUF machine words
This must be called after the 'file' has been initialized
with FZFILE, and before it is used with FZIN or FZOUT.
Different memory areas may be connected by recalling this
routine any number of times;
see section 
for explanations.