Wednesday, 28 January 2015

VSAM Part4 Questions and Answers

31. What more info you should give in the DD statement while defining the next generation of a GDG?
Give (+1) as the generation number, give (new, catlg) for disp, give space parameter, can give the DCB parameter if you want to override the DCB of the model dataset.

32. Assuming that the DEFINE JCL is not available, how do you get info about a VSAM files organisation?
Use the LISTCAT command.

33. Using Alternate Indexes in CICS program?
FCT entires must be created for both base cluster and the path. To read using the alternate index, use the DD name of the path in CICS file control commands.

34. Using Alternate Indexes in Batch program?
In the JCL, you must have DD statements for the cluster and for the path9s). In the COBOL program, SELECT ... ASSIGN TO ddname for base cluster RECORD KEY IS... ALTERNATE RECORD KEY IS ...

35. What is a LDS (Linear Data Set) and what is it used for?
LDS is a VSAM dataset in name only. It has unstructured 4k (4096 bytes ) fixed size CT's which do not contain control fields and therefore from VSAM's standpoint they do not contain any logical records. There is no free space, and no access from Cobol. Can be accessed by DB2 and IMS fast path datasets. LDS is essentially a table of data maintained on disk. The 'table entries' must be created via a user program and can only be logically accessed via a user program. When passed, the entire LDS must be mapped into storage, and then data is accessed via base and displacement type processing.

36. What is the meaning of the DEFINE MODEL parameter?
It specifies whether Daniela Pestova or Yamila - oops! Wrong models! The MODEL parameter allows you to model your cluster by modeling it after an existing cluster.

37. What are the three levels of definition for the VSAM DEFINE?

38. What is the utility program closely associated with VSAM?
IDCAMS, the access mehtod services utility.

39. What is the VSAM-code field?
It is a COBOL II enchancement to VSAM batch processing expanding the FILE STATUS field. It is defined in WORKING-STORAGE as a six byte group item with three two byte elements, the normal return code, the function code and the feedback code.

40. What is the meaning of dynamic processing?
It's rarely used. It means one program uses both sequential and random processing for a VSAM KSDS file.

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