Provide the ability for DSS to be able to scratch and reallocate an in use (ENQed) dataset that is not the actual dataset in use during a logical copy operation.

why not just provide a NOENQ option

To explain the scenaro futher:

I have an "program products" sysres that is an extension of IBM OS sysres. There is a maintenance
version of that sysres, just like you have a maintenance IBM sysres that you apply SMP/E maintenance to.  The PP sysres gets cloned along with the IBM sysres via full volume disk to disk copies. That is not a problem.  

That program products sysres has perhaps 40 IBM / ISV products. All the datasets are indirectly catalogued via &SYSRn.  Program product SMP/E target libs are copied (and renamed during the copy) to the PP maintenance sysres at various time.  When maintenance for any give product is applied (or an upgrade) and is ready to roll out the sysprog copies the SMP/E targets to this maintenance sysres.  So think of it as a volume were changes are staged for production.  Then after cloning, the changes are rolled out as a package, be it with IBM OS maintenance, one product, several products, or any combination like that.   This is done via rolling IPLs in a sysplex environment so as not to cause any application outages (usually half the LPARs one month, the other half the next month).   Almost every product's main loadlib is in the LNKLST and ENQed - at least anything that has associated production JCL. Other libraries are also ENQed, TSO CLIST / EXEC libraries, ISPxLIBs etc. 

So many of these datasets being "staged" prior to cloning are ENQed.  If the input library
in the copy is larger than the one on the maintenance sysres volume already there, that is when DFDSS fails.  If DFDSS doesn't have to scratch / reallocate the dataset that already exists to make it larger to accommodate the input data set size,  it works fine.

Here is a sample of the copy process with DFDSS, only there would be many more
libraries copied / renamed than just a single one for almost all products. 

//SYSIN    DD  *                                
 COPY DS( -                                     
   INCLUDE( -                                   
            smphlq.product.V6R3.LINKLIB -       
           )  -                                 
        )  -                                    
  RENAMEU( -                                    
           (smphlq.product.V6R3.LINKLIB -       
              prodhlq.product.LINKLIB)    -     
             ) -                                
  SHARE TOL(ENQF)   PROCESS(SYS1)     -         
  BYPASSACS(**)   -                             
  NULLSTORCLAS    -                             
  LIDY(inpvol)    -                             
  OUTDYNAM(outvol,SYSALLDA)           -         
  REPLACEUNCONDITIONAL -                        
  WAIT(2,2)  ALLDATA(*)  ALLEXCP                
/*            

If prodhlq.product.LINKLIB is ENQed (in this case you can presume it is due to being in the LNKLST on the driving system), you get this error:

ADR497E (001)-CATLG(07), A CATALOG ERROR OCCURRED WHILE DELETING UNCATALOGED DATA SET prodhlq.product.LINKLIB. RETURN CODE IS 102, REASON CODE IS FP-007

ERROR OCCURRED WHILE DELETING UNCATALOGED DATA SET        

                          

Better title - "Provide abilty for DSS to be able to scratch and reallocate an in use data set name that is not the actual dataset in use during a logical copy operation."