Editing Data set (IBM mainframe) (section)

===GDG JCL & features===
Generation Data Groups are defined using either the BLDG statement<ref>{{cite manual
 | title       = OS Utilities
 | id          = GC28-6586-15
 | date        = April 1973
 | edition     = Sixteenth
 | section     = BLDG (Build Generation Index) Statement 
 | section-url = http://bitsavers.org/pdf/ibm/360/os/R21.7_Apr73/GC28-6586-15_OS_Utilities_Rel_21.7_Apr73.pdf#page=269
 | page        = 269
 | url         = http://bitsavers.org/pdf/ibm/360/os/R21.7_Apr73/GC28-6586-15_OS_Utilities_Rel_21.7_Apr73.pdf
 | series      = IBM Systems Reference Library
 | publisher   = [[IBM]]
 | access-date = May 19, 2022
 }}
</ref> of the IEHPROGM utility or the DEFINE GENERATIONGROUP statement<ref>{{cite manual
 | title       = OS/VS Access Method Services
 | id          = GC26-3836-1
 | date        = May 1974
 | edition     = Second
 | section     = Defining a Generation Data Group 
 | section-url = http://bitsavers.org/pdf/ibm/370/OS_VS2/Release_2_1973/GC26-3836-1_OS_VS_Access_Method_Services_May1974.pdf#page=107
 | pages       = 107–110
 | url         = http://bitsavers.org/pdf/ibm/370/OS_VS2/Release_2_1973/GC26-3836-1_OS_VS_Access_Method_Services_May1974.pdf
 | series      = Systems
 | publisher   = [[IBM]]
 | access-date = May 19, 2022
 }}
</ref> of the newer [[IDCAMS]] utility,<ref name=How2>{{cite web
   |title=IBM How to create and use Generation Data Groups (GDG)
   | website=[[IBM]] | date=2 March 2012 |url=https://www.ibm.com/support/docview.wss?uid=swg21422334
   |quote=Create a GDG... IDCAMS will do it}}</ref> which allows setting various parameters.
* {{code|LIMIT(10)}} would limit the number of generations limit to 10.
* {{code|SCRATCH FOR (91)}} would retain each member, up to the limited#generations, at least 91 days.

IDCAMS can also delete (and optionally uncatalog) a GDG.<ref>{{cite web
  |title=IDCAMS – Create and delete GDG base using JCL
  |url=http://code.xmlgadgets.com/2011/05/16/idcams-create-and-delete-gdg-base/comment-page-1}}</ref>