How to change Max length of username in aix

On AIX 5.3 to change default length of username:

# chdev -l sys0 -a max_logname=9
sys0 changed

To check the current length of username:

# lsattr -El sys0 -a max_logname
max_logname 9 Maximum login name length at boot time True

# getconf LOGIN_NAME_MAX 21