Can inquiries somehow be done against copies of history files? If I take a backup before running the cleanup utility, can I later view information from the backup file?
It is not possible to access "backed up" history records directly from XCOM. In order for XCOM to access history records, they MUST be in an XCOMHIST data set that is ONLINE to an XCOM server.
While we do not supply a utility to view these files, you can use EasyTrieve or similar report writing software to extract and report on specific history information from the archived datasets.
Please also see TEC510824 How to get a Sequential file from XCOM History file for reporting or other purposes.