What is mempages?

Hello !

I was looking at the document to find out how the default size of maximum file descriptor is decided by system.

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Performance_Tuning_Guide/sect-Red_Hat_Enterprise_Linux-Performance_Tuning_Guide-Configuration_tools-Configuring_system_memory_capacity.html#sect-Red_Hat_Enterprise_Linux-Performance_Tuning_Guide-Configuring_system_memory_capacity-File_system_parameters

In the document , there is a calculation ,

(mempages * (PAGE_SIZE / 1024)) / 10

What is "mempages" and how can I check the default size of this value?

Thanks,
Yu Watanabe