The Check Password Block command provides the same function as the system V6R1
support to control users who attempt to change their password too frequently.
The system supports checking with the use of CHGPWD, but not with CHGUSRPRF.
CHKPWDBLK is intended to be placed in a program that uses CHGUSRPRF to change
passwords, but also wants to ensure infrequent changes. TAA9897 is sent as an
escape message if the time limit has not passed.