NCL VSAM Techniques › Initialization and ACB Open Processing

Initialization and ACB Open Processing

You can allocate and open UDBs at any time by using the ALLOCATE and UDBCTL commands. With certain UDBs, you might want to use some of the more advanced VSAM facilities that your product supports. For example, you might want to specify use of the LSR pool or sequential insert strategy (SIS) to improve system performance.

Use of these optional facilities must be requested on the UDBCTL command at open time. During the open process, a VSAM ACB is generated for each data set and an open attempted. If the open fails, the system internally links to IDCAMS to perform a verify of the data set. Therefore, it is not necessary to include verify steps in the system JCL.