C functions in RPG

List,
        I'm trying to call C functions for the first time. I get "name or
indicator is not defined" compile errors with I use the following code:

        /free
          num = atoi(field);
        //end-free

        Could it be that I need a certain library in my library list?
        Please excuse the newbie question, but I searched the archives for
specific code examples and didn't see anything that indicated having to
specify a certain library.
            BTW, both 'num' and 'field' are defined, so I can only assume
the compile can't find the atoi function.

        Thank you!

John Furniss
Allied Machine & Engineering Corp.
iSeries Application Programmer
Phone (330) 343-4283 Ext. 8371
email: jfurniss@xxxxxxxxxxxxxxxxx