How CULLVSAM Works

For sequential reads using a pointed start, CULLVSAM uses a key control statement to target the first VSAM record for the read. The key control statement specifies:
- A relative byte address for entry-sequenced files
- A key for key-sequenced files
After CA Culprit finds the target record, records are delivered sequentially to the input buffer until the end of the file is reached. If the starting record is not found, the read starts at the record with the next highest key.
For direct reads, CULLVSAM requires three files:
- The VSAM source file
- A sequential file (key file) that contains records with either key values for a KSDS file or relative byte addresses for an ESDS file
- A VSAM control file to define the key file
Upon execution of CULLVSAM, CA Culprit delivers the key file record to the beginning of the input buffer, followed by the retrieved VSAM record and the RDW, which is a binary field that overlay the last two bytes.