When the SAS^® system opens a direct access bound library, it verifies whether the actual number of blocks in the data set (as reported by the z/OS operating system) matches the expected number of blocks (based on information stored in the library header block). This check helps to ensure that the library has not been truncated or damaged since the SAS system last processed the library. When the DLTRUNCHK option is in effect, the SAS system will refuse to process the library if the actual block count (reported from z/OS) is less than the internal count from library header.

In the past, if you specified the NODLTRUNCHK option, the SAS system allowed read and write access to the library, even if the actual block count was less than the internal block count.

Therefore, a hotfix has been released to prevent write access to truncated libraries. When you apply this hotfix, if NODLTRUNCHK is in effect, only read-only access will be permitted to a library that appears to be truncated. As before, neither read nor write access to the library will be allowed if DLTRUNCHK is in effect.

It is strongly recommended that customers specify DLTRUNCHK as the default.

The hot fix also includes features to help diagnose the following problem and limit its impact.

Several customers have reported sporadic cases in which a direct access bound library is missing a block at the end of the first volume. In almost all cases, this problem was first noticed after the library was recalled via HSM. The problem has occurred after recalling the library data set from ML1 (disk) as well as after recalling from ML2 (tape). Attempting to read from such libraries has also resulted in page validation errors in some cases. The SAS system will treat such libraries as truncated.

Recommended Customer Actions:

1. Apply this hot fix as a preventive measure, even if your installation has not experienced any incidents of library truncation. This hot fix will help to avoid further damage, and in some cases, might make it possible to reconnect to the original HSM migrated copy of the library, which is important for diagnostic purposes.
2. If you have not yet applied the hotfix and you receive a SAS message regarding library truncation, do NOT attempt to process the library with NODLTRUNCHK in effect, or, with DISP=OLD until SAS Technical Support has diagnosed the problem and provided additional recommendations.
3. If you have applied the hotfix, the SAS system will automatically prevent write access to truncated libraries. However, please contact SAS Technical Support for recommendations if you receive the following message when processing a direct access bound library. Note that this message results in a condition code of 8 from the SAS job step, provided that DLTRUNCHK is in effect.
   

   ERROR: Library data set data-set-name does not comply with RECFM=FS requirements or is truncated.