file buffer size too small

Hi,

I need to read a big file that containt a matrix. I read the matrix by 
line, but I think PR_read use a buffer too small for a line. (My program 
spent 400s in system time and 35s in user time...) The environment 
variable BUFSIZ used by fread is smaller then a line and I suppose NSPR 
use buffer of this size. With fread, i can use setvbuf to specify the 
buffer size. I didn't find any such function in NSPR. Do you know how I 
can do it as I would prefer continue using NSPR?

thanks for your time

Frédéric Bastien