Compress PDS

How did you compress a pds? explain in detail?

Questions by medamahendra   answers by medamahendra

Showing Answers 1 - 27 of 27 Answers

Gousiya Mulla

  • Jun 20th, 2008
 

After a PDS has been subjected to a high volume of activity such as replacing members, adding new member and deleting members there may be unusable gaps or spaces between members stored within the PDS. A compress function using IEBCOPY is provided to compress the members and consolidate all the gaps or spaces into a single area within the PDS.

Ex: Command :
//COMPRESS DD  DISP=SHR,DSN=MFI01.SIMOPROD.JCLPROC1
//SYSIN    DD  *
COPY INDD=COMPRESS,OUTDD=COMPRESS
/*

kckinney

  • Sep 3rd, 2010
 

The other answers deal with the first question adequately, but ignore the second.

A PDS member is written to a disk with a list of blocks designating where on that disk the member resides.
When a member is changed, it is rewritten to disk in a new location.  The TTR in the VTOC is updated, pointing to the changed member.  Meanwhile, the space previously occupied by the member is marked as free.
If there is enough churn on a PDS, this can result in a lot of unused free space.

A compress logically rearranges all the members using all the unused free space.

A very simple analogue is to compare it to a PC disk defrag.

Naturally, this question is a trick.  Any more, we just use a PDSE.  Answering the question without knowing this reveals how little you know.

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dharma

  • Feb 2nd, 2015
 

Using iebcopy utility we can compress pds

Code
  1. //in dd dsn=xxxx.xxxx.xxxx

    2. 

  2. //sysin dd   *

    3. 

  3.      copy outdd=in,indd=in

    4. 

  4. /*

    5.

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sai prasad

  • Dec 17th, 2015
 

We can compress a partitioned data set in two ways
1)by using line command Z before data set
2)by using IEBCOPY Utility
PROGRAM:
//SHRDV08A JOB NOTIFY=&SYSUID
//STEP1 EXEC PGM=IEBCOPY
//SYSPRINT DD SYSOUT8
//DD1 DD DSN=SHRDV08.SAI5.PDS5(USER DEFINED)
//SYSIN DD *
COPY INDD=DD1,OUTDD=DD1
/*

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Nagaraju

  • May 12th, 2017
 

1. Using line command Z.
2. IEBCOPY

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