Just putting in a little plug for TAATOOLS, there is a command that can retrieve this information:
                    Retrieve Job Attr 2A - TAA (RTVJOBA2A) 
                                                           
Type choices, press Enter.                                 
                                                           
System library list      (165)   SYSLIBL                   
Product libraries         (55)   PRDLIB                    
Current library           (10)   CURLIB                    
User library list       (2750)   USRLIBL                   
Subsystem                 (10)   SBS                       
Subsystem library         (10)   SBSLIB                    
Temp storage used MB    (11 0)   TMPSTG                    
Max temp storage MB     (11 0)   MAXTMPSTG                 
Thread count            (11 0)   THDCNT                    
End status                 (1)   ENDSTS  
Help                     Subsystem (10) (SBS) - Help                    
                                                                        
    The subsystem the job exists in if the job is active.  If used, the 
    return variable must be specified as *CHAR LEN(10).                 
                                                                        
                                                                                          
Reply or Forwarded mail from: Kenneth E Graap
-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Rich Loeber
Sent: Thursday, March 19, 2015 6:30 AM
To: Midrange Systems Technical Discussion
Subject: Finding Current Subsystem
   I think I'm having a brain cramp.  Is there an easy way in a CL program to
   find out what subsystem the program is currently running in?  I would have
   thought it would be available from RTVJOBA, but no dice.  I also looked at
   the values returned from the QUSLJOB API but I don't see it there either.
   Suggestions?
   Rich Loeber - @richloeber
   Kisco Information Systems
   [1]
http://www.kisco.com
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