Get and set terminal size

[Denis Mezhov via Digitalmars-d-learn]

I want use tgetnum for get terminal size
http://www.mkssoftware.com/docs/man3/curs_termcap.3.asp

extern(C):
int tgetnum(const(char) *capname);

calling a method from main
writeln(tgetnum(toStringz("li")));


I receive an error message
Undefined symbols for architecture x86_64:
   "_tgetnum", referenced from:
       _main in RSConsole.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to 
see invocation)


Does anyone know what the problem is?
Maybe there are other methods to get and set sizes of the Mac OS 
X console?