Rule: Avoid using the RALTER command with the NOCFDEF option to change an existing custom field.

When you define a custom field with the RDEFINE CFIELD command, some custom field attributes are assigned default values. You can change most attributes in the definition of a custom field using the RALTER CFIELD command with the CFDEF operand. However, if you use the RALTER command, default attributes are not assigned or changed. Therefore, you might change an attribute to a value that is incompatible with the data type. Certain attributes are interrelated so if you use the RALTER command, make changes carefully.

When you make a change to a custom field definition (whether you use RALTER or you delete it using RDELETE and redefine it using RDEFINE), any CSDATA values that you have already added for the custom field are not changed. For example, if you use the HOMEADDR keyword of the ALTUSER command to add a 50-character HOMEADDR value to the profiles of five users, and you subsequently reduce the maximum length of the HOMEADDR custom field to 20 characters, the HOMEADDR values for those five users are not changed. In this case, those five users will have 50-character HOMEADDR values even though the maximum length for the custom field is now defined as 20 characters.

Guideline: Consider using the RACF® ISPF panels to modify CFDEF segment values in CFIELD class profiles. The ISPF panels will display the current values in a CFDEF segment and allow you to update them using a simple user interface.

After you change a custom field definition, you must activate your change by having your system programmer execute the IRRDPI00 UPDATE command to rebuild the dynamic parse tables on all systems that will use the changed custom field.