You have also over-allocated your server memory. On a 64GB server, you should not try to get SQL to use 63GB.
There are many processes that need to use memory... start with the operating system, add anti-virus and other services, SQL Server processes that run outside the main SQL memory space, backups, etc, etc.
A rough rule is to allow 20% of your server memory for processes outside the main SQL memory space, so on a 64GB server you should start by setting maximum SQL memory to 51GB. When you have some memory usage stats, you can fine-tune this setting, which may then move either up or down.
Original author: https://github.com/SQL-FineBuild/Common/wiki/ 1-click install and best practice configuration of SQL Server 2019, 2017 2016, 2014, 2012, 2008 R2, 2008 and 2005.
When I give food to the poor they call me a saint. When I ask why they are poor they call me a communist - Archbishop Hélder Câmara