The DSPFD has outfile capability. What this means is that you can select *ALL files in a particular library and dump all this to a file on the iSeries you can then query. The OUPUT parameter is set to *OUTFILE to do this and it will prompt you for a file name and library to dump data to. Don’t worry if the file does not exist because the file will be created. Make sure you are not overlaying a file that already exists though. On the command there is a parameter that allows you to select physical files only and the type of information parameter should be set to *MBRLIST which will give you record couts.
The iSeries info center has a CL finder command that you can display all information regarding all operting system commands. This is a sure fire go-to for quick information on a particular command. Here is a link to the V5R4 InfoCenter site.
Hope this helps.