How can I convert an ISAM file to another format using VISION:Builder/Two?

Document ID : KB000024350
Last Modified Date : 14/02/2018
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Description:

This article discusses how to convert ISAM files to another format since IBM discontinued ISAM support as of z/OS 1.7.

Solution:

IBM discontinued support of ISAM files as of z/OS 1.7.

(See http://www.redbooks.ibm.com/abstracts/SG246755.html?Open )

If you have still have ISAM files, they can easily be converted to other formats using VISION:Builder. Since ISAM files are always keyed, KSDS VSAM will likely be the most common usage.

A job like the following would be executed under a z/OS release prior to z/OS 1.7 that still supports ISAM. This job reads in an ISAM file and writes the entire records out to a KSDS VSAM file. The VSAM cluster definition would have been predefined using IDCAMS.

Note the use of free-form M4INPUT syntax which has been available for several VISION:Builder releases.

   //CONVERT EXEC PGM=MARKIV                                                     
   //STEPLIB DD DISP=SHR,DSN=builder15.loadlib                                   
   //M4LIB   DD DISP=SHR,DSN=your.m4lib                                          
   //M4LIST  DD SYSOUT=*                                                         
   //M4OLD   DD DISP=SHR,DSN=oldISAMfile                                         
   //M4SUBF1 DD DISP=OLD,DSN=newVSAMdsn                                          
   //M4INPUT DD *                                                                
   CONTROL                                                                       
   FILE MASTER  INPUT   NAME oldisamFDname                                       
   FILE SUBF1  NAME subvsam                                                      
   EXTRACT     FILE subvsam     ENTIRE O     RECFM KEYVSAM                     
   /*      

If the ISAM files are used in existing VISION:Builder applications, existing File Definitions would change column 21 of the FD statement from I (fixed ISAM) or J (variable ISAM), to the new format, in this example, K (KSDS VSAM). No changes need be made to the applications that read these files, only this simple change to the File Definition.

Any existing VISION:Builder applications that create ISAM subfiles would change the I or J in column 56 on the E1 (or En) to a record format supported by z/OS such as E (ESDS VSAM), K (KSDS VSAM), F (fixed length sequential) or V (variable blocked sequential). VISION:Builder supports more formats such as DLI and DB2, but these are the most logical to minimize impact to existing applications.

This example shows a fixed-format statement from a legacy system that creates an ISAM subfile.

The statement is modified to create an ESDS VSAM subfile.

  SUBFILE E1                              NRNFILENAME6000J    

to

  SUBFILE E1                              NRNFILENAME6000K