Preparing to use subset pointers

For your program to use subset pointers, the pointers must be defined in the DBD for the DEDB, and in your program's PSB.

In the DBD, you specify the number of pointers for a segment chain. You can specify as many as eight pointers for any segment chain.

In the PSB, you specify which pointers your program uses; you define this on the SENSEG statement. (Each pointer is defined as an integer from 1 to 8.) You also specify on the SENSEG statement whether your program can set the pointers it uses. If your program has read-only sensitivity, it cannot set pointers, but can only retrieve segments using subset pointers already set. If your program has update sensitivity, it can update subset pointers by using the SET, SETCOND, MOVENEXT, and SETZERO options.

After the pointers are defined in the DBD and the PSB, an application program can set the pointers to segments in a chain. When an application program finishes executing, the subset pointers used by that program remain as they were set by the program and are not reset.