Why doesn't getconf recognize BUFSIZ?

Question

$ getconf BUFSIZ
getconf: Unrecognized variable 'BUFSIZ'

Is there a standard way to determine the BUFSIZ value from the shell? It’s enough to just write a simple C program to output the value, but I don’t quite understand why getconf does not.

Answer 1

Since BUFSIZ is a multi-arbial configuration parameter for the stdio library, not a system configuration parameter

Answer 2

The man / info page for sysconf lists the constant names that getconf can return values ​​for.