clarify LFS on Enterprise ES 3

[J. Patrick Mayo]

I'm having problems with backup software (BRU Server from Tolis Group). 
  It dies when backing up large files/systems.  Tolis support have told 
me that I need to update my kernel to at least 2.4.24 in order to 
handle files larger than 2 GB.  I searched the web a bit and it seems 
as though Large File Support is already enabled in 2.4.x kernels.

1) How do I tell if LFS is on or off?
2) If it is off, does my kernel support LFS and how would I enable it?  
Must I recompile?

I am using a dell box with Enterprise ES 3, 2.4.21-15.0.3.EL kernel.  
If anyone has any suggestions or could point me in the right direction, 
it would be greatly appreciated.