𝗖𝗢𝗕𝗢𝗟 𝗕𝗟𝗞𝗦𝗜𝗭𝗘 𝗕𝗲𝗵𝗮𝘃𝗶𝗼𝘂𝗿: 𝗧𝗮𝗽𝗲 𝘃𝘀. 𝗗𝗶𝘀𝗸 𝗢𝘂𝘁𝗽𝘂𝘁

While testing the same COBOL program, I observed different BLKSIZE behavior for tape and disk output datasets.

 

The COBOL program had the following settings:

 

• NOBLOCK0 compiler option was in effect.
• The FD definition did not contain BLOCK CONTAINS 0.

Tape output dataset

 

For a tape output dataset, the system assigned a BLKSIZE equal to the LRECL, regardless of whether BLKSIZE=0 was specified in the JCL.

 

In other words:

• With BLKSIZE=0 in JCL → BLKSIZE was assigned the same value as LRECL.
• Without BLKSIZE=0 in JCL → BLKSIZE was still assigned the same value as LRECL.

Disk output dataset

 

The behavior was different for a disk output dataset.

Regardless of whether BLKSIZE=0 was specified in the JCL, the system assigned an appropriate BLKSIZE as expected.

 

Fix for the tape output dataset

 

To address the tape dataset issue, I added the following clause to the COBOL FD:

BLOCK CONTAINS 0

 

After making this change, the system properly assigned the BLKSIZE for the tape output dataset as well, irrespective of whether BLKSIZE=0 was specified in the JCL.