If you are RACF-defined, you must enter the password defined in the RACF® data set as the value for password. The new password specifies the password that is to replace the current password. new_password must be separated from password by a slash(/) and, optionally, one or more standard delimiters (tab, blank, or comma). new_password is 1 to 8 alphanumeric characters long. This operand is ignored for non-RACF defined users. (Printing is suppressed for some types of terminals when you respond to a prompt for a password.)
With z/OS® V1R7 or later, the password and new_password can be in mixed case, if your installation has enabled RACF mixed case password support.
ref: https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.1.0/...
And I quote:
If you are RACF-defined, you must enter the password defined in the RACF® data set as the value for password. The new password specifies the password that is to replace the current password. new_password must be separated from password by a slash(/) and, optionally, one or more standard delimiters (tab, blank, or comma). new_password is 1 to 8 alphanumeric characters long. This operand is ignored for non-RACF defined users. (Printing is suppressed for some types of terminals when you respond to a prompt for a password.) With z/OS® V1R7 or later, the password and new_password can be in mixed case, if your installation has enabled RACF mixed case password support.