Setting max_fsm_pages

Should I set the max_fsm_pages to the value reported (vacuum verbose) as
pages stored or the value reported as total pages needed? I ran full +
analyze vacuums in my database (vacuumdb -f -z -v <database name>) a couple
of times and I got the following reports:

INFO: free space map: 454 relations, 22274 pages stored; 147328 total pages
needed

DETAIL: Allocated FSM size: 1000 relations + 20000 pages = 178 kB shared
memory

And

INFO: free space map: 454 relations, 22242 pages stored; 147328 total pages
needed

DETAIL: Allocated FSM size: 1000 relations + 20000 pages = 178 kB shared
memory

I am not sure if I need to raise the max_fsm_pages to something larger than
22242 (e.g. 40000) or larger than 147,328.