You can't change the definition of CZMG (or rather, you can change it but you can't save your changes) because it belongs to a system group. Groups with names starting with "DFH" are system groups and can't be changed.

To change the definition of a predefined transaction such as CZMG, you need to copy it to a user-defined group, change the definition there, and then make sure your definition takes precedence in the group list. In this case, you could copy just the CZMG definition to a new group and give that group precedence over DFHOPER, or copy all of DFHOPER to a new group and use the new group in place of DFHOPER in your startup list.

Here's an example of the former approach:

1. I will use a region that already has a user-defined SIT and startup list. The startup list is named "MWWSTRT".
2. Using ESMAC, I create a new group "MWWOPER". In the description field I put "Overrides for DFHOPER", so I remember what this group is for.
3. I view the entry for CZMG in DFHOPER and click the Copy button. I copy it to MWWOPER.
4. Using the "By Groups" view in ESMAC, I edit the copy of CZMG in MWWOPER, uncheck RLS, and apply the change.
5. I view my startup list MWWSTRT and add MWWOPER to it. Groups lower in the list supersede groups higher in the list, so the definition of CZMG in MWWOPER will override the one in DFHOPER.
6. I restart the region so these changes can take effect.

However, I don't know that removing RLS (resource-level security) will have any effect on what you're trying to do. I don't know that calling DFHZCZMG from a user application is allowed, or what the parameters for it are.

Thanks for the information.