Data collection exit support

Data collection provides the facility to skip, modify, or replace data collection records. The user program can specify the address of an exit and the address of a 100-byte control area. The exit is invoked prior to writing each data collection record. The exit is also supported directly using DCOLLECT, either using IDCDCX1, or the EXIT(exit) keyword.

The data collection exit, shown in Figure 1, must be reentrant, and must be written to process below the 16MB line:

Figure 1. Exit for Data-Collection Support

The following registers are used with the exit described in Figure 1:

On entry, register 1 contains the address of the parameter list. The parameter list must reside below the 16MB line. The first and only address in the parameter list is an address to the ARCUTILP data area.
On entry, register 2 contains the address of a 100-byte control area. This 100-byte control area is for the system programmer's use when writing the exit. For example, the work area can contain counters, totals, or other statistics.
On entry, register 13 contains the address of a save area sufficient to store the program state (72 bytes).
On entry, register 14 contains the return address.
On exit, register 15 contains the return code. This return code is also available in the ARCUTILP data area. See Table 1 for a description of possible return codes and reason codes.