I think there's a little confusion on terms here, you mention JCL but it sounds like you're talking about AE Scripting. JCL is the unix/windows/etc. commands sent to the agent.
I don't think you can do this with just AE script, but you can if you use a SQLI vara to query the database for a list of active jobs. This query would list all active jobs along with the info you might want:
select EH_Client, EH_Name, EH_ah_Idnr, EH_ParentAct, EH_ParentPrc
from EH
You could then use prep_process_var() to filter down to just the children of the workflow you're interested in.
Unfortunately subflows would not directly show their top workflow parent, for that you'd need a recursive query, or you could call sys_act_top_nr() on each runid (probably slow if you have a very active system).