The *!SASROOT* directory is created when SAS is installed on a system. The default location (directory) is /usr/local/SAS/SASFoundation/9.x, but it can be stored anywhere in a file system (x = release). (Apparently, under Windows, the default location is c:\program files\SASHome).
The !SASROOT directory is the root for all SAS Foundation products.
!SASROOT/sas: the SAS executable that is used to invoke a SAS session. There are language aware executables under !SASROOT/bin, for exmaple !SASROOT/bin/sas_en for english sessions etc.
!SASROOT/sasv9.cfg: the main configuration file. It is independent from the language used when a SAS session was started.
Language dependent configuration files can be put under !SASROOT/nls/