For the entry codes described in Table 2 and Table 1, the performance monitor exit can use this 8-byte user data field, originally initialized to 0, for any purpose. For example, the exit could use this field to store the address of a storage area obtained dynamically. This field is cleared to zero when the performance monitor exit becomes inactive.

The last 4 bytes can be used to uniquely identify an exit's level or version. The last 4 bytes are displayed following subsequent use of the DISPLAY EXIT command. See z/OS Communications Server: SNA Operation for a description of the DISPLAY EXIT command.