I don't know what version of UNIX you run but maybe you need to check out man ctime

I think you mean the st_ctime argument of stat. You should follow your own advise:

st_ctime

Time when file status was last changed (inode data modification). Changed by the chflags(2), chmod(2), chown(2), creat(2), link(2), mkdir(2), mkfifo(2), mknod(2), rename(2), rmdir(2), symlink(2), truncate(2), unlink(2), utimes(2), write(2) and writev(2) system calls.

$ touch a

$ perl -MFile::stat -wle'print "".localtime( stat("a")->ctime )'
Fri Aug 21 13:31:40 2009

$ sleep 2

$ perl -MFile::stat -wle'print "".localtime( stat("a")->ctime )'
Fri Aug 21 13:31:40 2009

$ chmod go= a

$ perl -MFile::stat -wle'print "".localtime( stat("a")->ctime )'
Fri Aug 21 13:32:25 2009
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I don't know what version of UNIX you run

The man page is from FreeBSD 7.2. You can view the man pages for about 100 different systems if you follow the link above, and I'm sure you'll find similar results for all of them.

The example was executed on Debian Linux (etchnhalf)

$ man -f ctime
asctime, asctime_r, ctime, ctime_r, difftime, gmtime, gmtime_r, 
localtime, localtime_r, mktime, timegm, timelocal (3) - convert 
date and time to ASCII
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This has nothing about creation time in it. Look here and stat(2) for more details about the lack of creation time. There is mtime (modified - file data change), atime (access time), and ctime (changed time - inode data modifcation).