In the following, when the HLLX DETACH is issued there is the CMNx482I message, but it is not followed by ‘CMNx483I CMNSTART Termination of HLL exit address space complete’.  Instead, it has the message ‘CMNx499E HLLX address space is no longer active.’:                  

MODIFY CHGMAN.CHGMAN,CMN,DETACH,HLLX                                   
SER0850I Operator command: CMN,DETACH,HLLX                             
CMN1482I CMNSTART Termination of HLL exit address space requested.     
CMN1499E HLLX address space is no longer active.                       
IEA995I SYMPTOM DUMP OUTPUT  738                                       
SYSTEM COMPLETION CODE=0C4  REASON CODE=00000011                       
 TIME=08.22.24  SEQ=37663  CPU=0000  ASID=0458                         
 PSW AT TIME OF ERROR  078D0000   B537E8A0  ILC 4  INTC 11             
   ACTIVE MODULE           ADDRESS=00000000_35379000  OFFSET=000058A0  
   NAME=CMNSTART                                                       
   DATA AT PSW  3537E89A - 83484D70  83489140  3070A714                
   AR/GR 0: 00000543/00003DAA_91000000   1: 00000000/00000000_3537A528 
         2: 00000000/00000000_00000014   3: 0101004D/00000000_2C688FB0 
         4: 0101004D/00000000_3533F374   5: 00000000/00000000_B537E810 
         6: 00000000/00000000_B537ADCE   7: 00000000/00000000_B537E8A0 
         8: 00000000/00000000_3537A1AC   9: 00000000/00000000_353791AC 
         A: 00000000/00000000_35258EC8   B: 00000000/00000000_00007000 
         C: 00000000/00000000_35334000   D: 00000000/00000000_35342128 
         E: 00000000/00000000_0000030E   F: 00000000/00000000_00000000      
 END OF SYMPTOM DUMP                                                        
IEA993I SYSMDUMP TAKEN TO XX.YYYY.CHGMAN.V82.SYSMDUMP.G1128V00              
SER0953E Task abnormally terminated: Comp=S0C4 Function=MODIFY/ NSI=3520834E
MODIFY CHGMAN.CHGMAN,CMN,ATTACH,HLLX                                        
SER0850I Operator command: CMN,ATTACH,HLLX                                  
IEA995I SYMPTOM DUMP OUTPUT  822                                            
SYSTEM COMPLETION CODE=0C4  REASON CODE=00000004                            
 TIME=08.22.27  SEQ=37664  CPU=0000  ASID=0458                              
 PSW AT TIME OF ERROR  078C3000   B520834E  ILC 4  INTC 04                  
   ACTIVE MODULE           ADDRESS=00000000_35200000  OFFSET=0000834E       
   NAME=SERVER                                                              
   DATA AT PSW  35208348 - 00E040F0  81809004  81404100                     
   AR/GR 0: 35342000/00003DAA_3537A32E   1: 00000000/00000000_35334010      
         2: 00000000/00000000_35334018   3: 0101004D/00000000_3537A30C      
         4: 0101004D/00000000_3533F374   5: 00000000/00000000_3537C0D0      
         6: 00000000/00000000_B537ADCE   7: 00000000/00000000_3537A3BC      
         8: 00000000/00000000_3537A1AC   9: 00000000/00000000_00007000      
         A: 00000000/00000000_352083C8   B: 00000000/00000000_352093C8      
         C: 00000000/00000000_35334000   D: 00000000/00000000_353420E0
         E: 00000000/00000000_B520811A   F: 00000C05/00000000_000003B9  

Here is an example of the HLLX DETACH/ATTACH issued and the expected messages (where 'x' is the ZMF task subsystem ID):

MODIFY SERSUPIx.SERx,CMN,DETACH,HLLX                                
SER0850I Operator command: CMN,DETACH,HLLX                          
CMNx482I CMNSTART Termination of HLL exit address space requested.  
CMNx483I CMNSTART Termination of HLL exit address space complete.   
MODIFY SERSUPIx.SERx,CMN,ATTACH,HLLX                                
SER0850I Operator command: CMN,ATTACH,HLLX                          
CMNx480I CMNSTART Waiting for HLL exit address space to initialize. 
CMNx481I CMNSTART Successfully connected to HLL exit address space. 
CMNx492I Start of HLLX active exits list:       

Full article: https://portal.microfocus.com/s/article/KM000016783