Is galera.cache cleaned during mysql restart

Say i want to bootstrap a cluster. All nodes are down and have different seqno’s.
I picked the furthest advanced node and bootstrap the cluster from it. Is galera.cache on that node cleaned at that point?
Documentation says galera.cache is preallocated. I guess i’m not clear on that bit.
So if its cleared when mysql starts, there’s no way to IST bootstrap a cluster?