Creation of Physically sequential file using ISPF.

Creation of physically sequential dataset using ISPF.

    

    First I will show you how to create PS (physically sequential) dataset.

Physical sequential dataset where you can stored your data but for huge number of record it is time consuming to retrieve the record so VSAM(Virtual Storage Access Method ) came into picture. Now you just concentrate on how to create PS dataset.

The name of dataset is 44 char with 8 character in a group then dot . you can use national characters like @,#,$,% etc but it should not be at the start.

XXXXXXXX.XXXXXXXX.XXXXXXXX.XXXXXXXX.XXXXXXXX.XXXX

Option ‘a ‘ to allocate a dataset then give the name of dataset like below.

Just to know it is ps file I have written at last.ps so from name only I can understand that it is PS file.

Note--   The first 8 character is your ID. I have erased it due to policy purpose.

Then you will forward towards next screen where you have to give storage specification like  space in Track,Cylinder,KB,MB,Bytes etc.

 

  

All first fields like management class,volume serial etc.is  system admin defined.Space is calculated as per the requirement.

·          Relation between Byte,kilobyte,megabyte

       8 Bits = 1 Byte
      1024 Bytes = 1 KiloByte
      1024 KiloBytes = 1 MegaByte

·                   

       Relation between Track and Cylinder.

      1 TRK=56,664 bytes
     1 CYL=15 TRK=849,960 Bytes per Cylinder

See more information on   http://www.lascon.co.uk/hwd_3390_disks.php

Primary quantity is amount of required space for our dataset and if this space is full then data stored on the secondary space defined by secondary quantity.

Directory Block is defined for PDS dataset only. For PS dataset it is blank or zero.

Record format Types-

1   1)  Undefined assigned by U.

    2)    FB means Fixed block for eg. A block with record length=50 and block size of 5000 so we creat a 1 block of toal 5000 bytes in length in our assigned space.

    3)  VB  means variable Block here record length is fixed but block length is not  fixed.

    4)    F for Fixed length record.

    5)    V for Variable length record.Data set name type is blank for PS.

      After pressing enter you can get a message like “ Dataset Allocated”
 
      You can see the file in dataset list as below.

r    From ISPF main menu enter 3 for utility then press 4 i.e DSlist then press enter.

You can find your created PS file there.........