Altering GDG base

• Parameters of GDG base can be modified using ALTER command
• For example, in section- ”Creating GDG base”, we created 'PAYROLL.SALARY.MONTHLY' GDG base with NOEMPTY and SCRATCH sub-parameter, but now we 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.