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Q: How to create image copy?
Answer:
COPY utility creates backup. COPY TABLESPACE db.ts. FULL or INCREMENTAL. SHRLEVEL REFERENCE or CHANGE. Store in GDG for versions. Regular copies essential for recovery. COPYTOCOPY duplicates copies.
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Q: How to pass data between steps?
Answer:
Use DISP=PASS to pass datasets. Receiving step references same DSN. Or use symbolic parameters. GDG allows relative references (+1 created, 0 passed). Temporary datasets (&& prefix) auto-pass. SYSIN instream data copied to subsequent steps.
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Q: How to define GDG in JCL?
Answer:
Create GDG base with IDCAMS DEFINE GDG. Reference generations: DSN=MY.GDG(+1) for new, DSN=MY.GDG(0) for current, DSN=MY.GDG(-1) for previous. DISP=(NEW,CATLG) for +1. Model DSCB needed for SMS-managed datasets.
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Q: Explain generation data groups
Answer:
GDG maintains versions. Base defined with IDCAMS: DEFINE GDG NAME(base) LIMIT(10) SCRATCH. Reference: base(+1) new, base(0) current, base(-1) previous. LIMIT controls kept generations. NOEMPTY/EMPTY for empty condition.
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Q: How to create temporary VSAM?
Answer:
Use REUSE attribute. Or define/delete in same job. Or use GDG-like naming. JCL doesn't support && for VSAM. IDCAMS DELETE at job end. Cannot be truly temporary like sequential.