Information
Defines the minimum number of alphabetic characters in a password.
In setting the minalpha attribute, it ensures that passwords have a minimum number of alphabetic characters.
Solution
In /etc/security/user set the default user stanza minalpha attribute to be greater than or equal to 3 :
chsec -f /etc/security/user -s default -a minalpha=3
This means that there must be at least 3 alphabetic characters (upper or lowercase) within a password.