Deletion stubs.
They are required if you have a replica of a database. If you are sure you have no replica's then you may reduce this number, whatever you do, do not tick the box on the left at the begginning of the line for this option, it is a separate function.
The deletion stubs will be removed when maintainance is done to the database for example a "load compact -c path\database.nsf", the number needs to be set to value that makes sense to the compactor task, "delete all stubs older than..." normally setting this value to 7 is the best option for a database that has no replica's. A weekly compact of the database with a program document can keep it clean.
I assume you are having issues with IDTable errors, If you are it might be too late to remove the deletion stubs, it would also mean that your compact task isn't finishing. In which case I would run an offline compact using the dosbox/command console from windows. Stop the Domino Server go to the Windows Domino directory and type "ncompact -c path\database", wait untill it finishes and note if it delivers error messages while compacting.
delstubs.exe, should only be used if you have a database with no replica's. It can help, but standard maintenance is the key, also check out domino defrag.
Sincerely
Douglas Bryant