Using DFSORT option NOBLKSET

The BLKSET option is the default when you invoke DFSORT. This allows DFSORT to use the efficient BLOCKSET techniques. When NOBLKSET is in effect, DFSORT falls back to use the conventional technique. The recommended setting is BLKSET.

DFSORT also uses the conventional technique in the following cases:
  1. Use tape device for intermediate work storage. You can avoid this restriction by using disk device instead of tape. Intermediate storage is specified using SORTWKdd statements.
  2. Use L5 in the RECORD statement of DFSORT OPTION control. L5 specifies the average record length. Instead of using L5, the same can be specified by using the AVGRLEN=n statement.

The use of DFSORT conventional technique is allowed by COBOL V4.2 or earlier versions. It is strongly recommended that programs upgrading to COBOL V5 or later versions take the opportunity to migrate away from the conventional technique of DFSORT.

To provide compatibility with COBOL V4.2 and earlier versions and to tolerate this usage in COBOL V5 or later versions, apply runtime LE PTFs UI67483(V2R2)/UI67485(V2R3)/UI67486(V2R4) and follow the instructions to set up the JCL when executing the program.
Note: Those runtime PTFs apply to AMODE 31 only. DFSORT conventional technique is not supported by COBOL programs running in AMODE 64.