The answer is yes, system symbols can be used (like shown on the SYSSYM display) in this member. But here are more information:
Refer to the comments at top of SAMPJCL(USRM0004). It explains the default 'out of the box' naming convention is GSVBJvrs.
All necessary GSVBJxxx modules are provided and it is unnecessary for a user to use this USERMOD.
But if someone encounters a new JES service level before a PTF is issued to provide the new module, they can choose to run this usermod to create the new module (temporarily until a PTF is issued for it).
If they do this and use the default naming convention of GSVBJvrs, there is no need to specify any value on the system configuration option JES-Config-Module.
The only time you need to code JES-Config-Module is if you apply the usermod and make up your own module name. In general avoid doing that because it then forces use of a particular name, and 'disables' our functionality of looking for the appropriate name of GSVBJvrs to match the version of JES running on the system.