When you concatenate data sets with unlike attributes, no EOV exits are taken when beginning each data set.

The system treats the volumes of a striped extended format data set as if they were one volume. For such a data set your EOV exit is called only when the end of the data set is reached and it is part of a like sequential concatenation.

When the EOV routine is entered, register 0 contains 0 unless user totaling was specified. If you specified user totaling in the DCB macro (by coding OPTCD=T) or in the DD statement for an output data set, register 0 contains the address of the user totaling image area.

The routine is entered after the next volume has been positioned and all necessary label processing has been completed. If the volume is a reel or cartridge of magnetic tape, the tape is positioned after the tape mark that precedes the beginning of the data.

You can use the EOV exit routine to take a checkpoint by issuing the CHKPT macro (see z/OS DFSMSdfp Checkpoint/Restart). If a checkpointed job step terminates abnormally, it can be restarted from the EOV checkpoint. When the job step is restarted, the volume is mounted and positioned as on entry to the routine. Restart becomes impossible if changes are made to the link pack area (LPA) library between the time the checkpoint is taken and the job step is restarted. When the EOV exit is entered, register 1 contains the address of the DCB. Registers 2 - 13 contain the contents when your program issued the macro that resulted in the EOV condition. Register 14 has the return address. When the step is restarted, pointers to EOV modules must be the same as when the checkpoint was taken.

The EOV exit routine returns control in the same manner as the DCB exit routine. The contents of register 14 must be preserved and restored if any macros are used in the routine. Control is returned to the operating system by a RETURN macro; no return code is required.