Altering GDG base

• Parameters of GDG base can be modified using ALTER command
• For example, in above section- ”Creation of GDG base”, we created 'PAYROLL.SALARY.MONTHLY' GDG base with NOEMPTY and SCRATCH sub parameter, but we now have to modify it to EMPTY and NOSCRATCH respectively, in such situation we can use below ALTER command of IDCAMS utility
  //DEPTJOB JOB A123,’STEVE’ //STEPNAME EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * ALTER PAYROLL.SALARY.MONTHLY EMPTY NOSCRATCH /* //
• Now these modified features applies to existing generations as well as any new generations
• Be careful while altering LIMIT command as specifying a smaller number than the current LIMIT will cause generations to roll off the GDG. This is one of those cases where a typo (e.g., LIMIT(1) instead of LIMIT(11)) can have a big impact.