Subject Upgrade from superclassic to superserver


I am in the process of upgrading our Firebird database from 2.5.7 to 3.0.3. While making the upgrade, I want to switch from SuperClassic to SuperServer in order to gain better scalability. However configuring SuperServer i new to me. 

Background information:

The database server is a 16 core virtual machine with 128Gb of RAM, and ssd SAN. The database is about 100Gb and growing by 20Gb/year. Daily load is about 3000 concurrent web users. The server is running CentOs 7

Here is the configurations that i have come up with so far. Pagesize is 16K

Firebird config:

DefaultDbCachePages = 524288(8Gb) 

On the old server this was 1024. On the new server this value is the one that I am most concerned about, i hope that someone can guide me. I have seen values of up to 2M(32Gb) in other guides, and I tempted to do the same. 

FileSystemCacheThreshold = 1048576

The old server used default for 2.5.x

TempCacheLimit = 4294967296

Same as the old server

TempBlockSize = 2097152

Same as the old server

LockMemSize = 9437184

Same as the old server

LockHashSlots = 30011

Same as the old server

Regarding Centos:

Number of open files has been configured to 64K

Reading this Guide: vm.pagecache should be limited to 40-50% However it looks like vm.pagecache is not availabel in CentOs, should  vfs_cache_pressure be used instead? 

I hope that someone can point me in the right direction or give some feedback.