  Largest Buffered I/O Permitted? (Mailbox) 
 The Question is:
 
Is there a limit on the maximum size of a single read or write to a mailbox
 when using sys$qio and sys$qiow? If so, how can I change this value?
 
 The Answer is :
 
  The MAXBUF system parameter, most commonly.
 Answer written or last revised on  14-AUG-2001 
