From: joemonk64@gmail.com   
      
   > That is fine if you run program from start to end. But if you need    
   > to suspend program (normal thing in interactive use), then it    
   > in natural to swap such program to disc and reload in different    
   > place. But OS/360 did not support this. TSS-360 tried, but    
   > the project was failed.    
      
   True for TSS/360. Not true for TSO on OS/360, which ran just fine.   
      
   >    
   > Even in batch system relocation could be quite useful: MVT    
   > region had to allow for _maximal_ use, and were frequently    
   > much larger than strictly needed. With relocation it would    
   > be possible to enlarge regions, so much smaller initial    
   > region would be OK. IBM tests indicated that paging    
   > (going from MVT to MVS) allowed similar load using 3-4    
   > times less memory. Flexible regions would not give that    
   > much, but clearly would give large saving compared to    
   > MVT. Of course, once 370 got paging there was no    
   > reason for relocation register, but it would make    
   > sense for original 360.    
      
   MVT allowed for paging (but called rollout/rollin)...   
      
   Rollout/Rollin   
   Normally all storage requested by programs of a given step or task is assigned   
   from its region. However, if the rollout/rollin feature has been included in   
   the system, an additional region (or regions) may be temporarily assigned to a   
   job step to meet    
   storage requirements that cannot be filled from the step's region.   
   When such additional storage is required, the rollout/rollin routines try to   
   assign a new region to a step from unassigned storage in the dynamic area. If   
   there is not enough unassigned storage, the contents of a region already   
   assigned to another job    
   step is written on a direct access volume (rolled-out), and that region is   
   used by the step requiring the additional space. Later when the additional   
   region is no longer required, the step that was rolled out is read back into   
   the region (rolled-in) and    
   allowed to continue its operation.   
      
   http://www.bitsavers.org/pdf/ibm/360/os/R21.7_Apr73/GC28-6720-5_   
   VT_Guide_Rel_21.7_Aug74.pdf   
      
   Joe   
      
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