This is one of those subtle differences between the 'temporary' nature of the old parameter style FACILITY displays vs. the 'permanent' nature of the FACSTOR VSAM record FACILITY displays. Every facility in the matrix has an associated IN-USE bit that is OFF for all unused USERxxx facilities. The first time that facility is renamed using a MODIFY command, that IN-USE bit is turned ON and that is what causes it to be displayed in a FAC(ALL) type display. If you later use MODIFY to rename it back to the USERxxx name, or to any other name, the IN-USE bit always remains set and the facility will show up in the FAC(ALL) list. This works the same whether FACSTOR is active or not until the next IPL or re-cycle of the Top Secret address space. With FACSTOR(NO) the 'temporary' version of the facility matrix is wiped clean and completely rebuilt by your latest parameter file settings after an IPL or recycle of the Top Secret address space. This is what allows the USERxxx entries to go back to their native value for the IN-USE bit which is OFF. With FACSTOR(YES), the facility matrix is established from the 'permanent' FACSTOR VSAM record which permanently maintains the IN-USE bit for each facility entry no matter how many times you IPL or recycle Top Secret.