What does stat(2) st_size of directory represent?

i.e.:

$ ./stat_size /home/kian /home/reed
 /home/kian         512
 /home/reed        6144
$ ls -ld /home/kian /home/reed
drwxr-xr-x   3 kian  users   512 Jan 19  2001 /home/kian
drwxr-xr-x  75 reed  staff  6144 Oct 18 04:47 /home/reed

How does it figure out the 512 or 6144 (for a directory)?

This is the total number of 1K blocks used by files in the directory:

 $ BLOCKSIZE=1024 ls -la /home/kian
 total 9
 ...snip...

 $ BLOCKSIZE=1024 ls -la /home/reed
 total 128436
 ...snip...

This is the total for all 1K blocks in the directory (kian has no
sub-directories):

 $ BLOCKSIZE=1024 du -s /home/kian
 11      /home/kian

 $ BLOCKSIZE=1024 du -s /home/reed
 868105  /home/reed


What does stat(2)'s st_size of a directory entry represent?

Thanks,

   Jeremy C. Reed
   http://bsd.reedmedia.net/