No SHRUPD but still file locked

Hi 


Iam getting the following error very frequently
CALL PGM(YCTC1)                                       
  
    File YPOSF1 in QS36F in use, cannot be shared.    
        
    Function check. QRY1765 unmonitored by YCTC1 at
statement instruction X'0016'.                        
              
    QRY1765 received by YCTC1 at 1100. (C D I R) 


When i went onto check object locks on this file
YPOSF1 i found the following...
Job          User         Lock      Status         
Scope     Thread 
RBT_GDBPOS   D_MIRROR     *SHRRD     HELD          
*JOB             


when i went to check member locks i found the
following.....
                                  
                                    Lock              
            
     Job         User        Type    Lock     Status 
Share 
    RBT_GDBPOS  D_MIRROR    MBR     *SHRRD    HELD    
   
                            DATA    *SHRRD    HELD    
   

Iam nt finding any locks like *SHRUPD(shared update)
but still wondering why this error coming so
frequently.Iam nt seeing ant locks like SHRUPD.Iam
seeing only *SHRRD.
In the above scenario i check locks and take Retry
from the response codes.
Can someone suggest me why Iam getting this error even
though there are no locks like *SHRUPD  ??
and how do I avoid this error coming again?
This is really making us to wait for some time to
check locks n come back then take Retry.I would like
to avoid this error !!!

Thank you so much for your help in advance

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