How to estimate Work files size to be used by CA IDMS REORG?

Document ID : KB000056611
Last Modified Date : 14/02/2018
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One of the most common questions when using REORG, is how to estimate the Work File dataset sizes. Within CA IDMS REORG setup execution options, there's syntax " ESTIMATE workfile sizes" that estimates the size of all work files after UNLOADing the data. Or alternatively you can execute this statement as a separate job to get this report. 

CREATE DSMODEL W*

DSN 'YOURHLQ.REORG.&DD'

UNIT SYSDA                                                          

SPACE TRK(100,100)                                                   

 BLKSIZE 12004                                                       

 ;                                                                   

 REORG SEGMENT APPLDICT USING IDMSNWKU                               

 AREA DDLDML                                                         

 RELOAD INTO APPLDICT USING IDMSNWKU DMCL RELD1600                   

 DIVIDE PROCESSING 4 WAYS                                            

 REUSE WORKFILES                                                      

 AS SORTEXIT                                                         

 ESTIMATE WORKFILE SIZES SUBMIT                                      

 STOP AFTER UNLOAD                                                   

 CREATE ALL WORKFILES                                                

 SHARE                                                               

 NOTIFY 10                                                           

 ;         
Please see the IDMS 17.0 SP1 Release Summary, page 274 7.12 REORG Enhancements 
Syntax for REORG ESTIMATE workfile sizes 

and also Chapter 7.12.1.3 Work Files 

"Work file creation: REORG can create work files dynamically, or you can 
manually create them prior to beginning the UNLOAD and/or RELOAD phases 
of REORG execution. Regardless of how the files are created, it is a good idea 
to halt execution after setup to determine what work files are needed by 
examining the report produced by REORG 


If using dynamic work file creation, you must specify the attributes of the work 
files using one or more CREATE DSMODEL statements. REORG creates the 
files as directed by the CREATE WORKFILE clause or at the time they are first 
accessed. Dynamically created work files, other than DBKEYS files, are deleted 
automatically during the cleanup phase. 

If you want to use REORG's size estimates to create a file, code a DSMODEL 
without a primary SPACE allocation. You can code a SPACE parameter with 
just a unit type (TRK, CYL, or blksize) and no value for primary allocation." 

Example of the REORG Task and Work File Usage report is in the REORG Status Report –Section 5:

References:

TEC427060 How to get started on the first execution of the new REORG utility to expand a database area.

TEC4820704 CREATE DSMODEL statement in REORG for sort work datasets.

TEC587833 Specifying space for REORG work files, to avoid a B37, D37, E37 abend.