Each time a log data set is to be allocated, the TRANSMIT pre-allocation exit, INMXZ21R, receives control. This exit may be invoked multiple times for each TRANSMIT operation. This exit can allocate the log data set, modify the data set name, or take no action. If the exit chooses to allocate the data set, the exit must pass the file name back to the TRANSMIT command. If the exit modifies the data set name, the TRANSMIT command will then allocate the data set for the exit if the exit has not already done so.

Under normal operations, the TRANSMIT command frees the log data sets automatically. Therefore, even if the exit allocated the log data set, the data set is freed when the command processor terminates normally.

During TRANSMIT processing, the allocation of the log data set occurs after the TRANSMIT command has freed the output file. This is after exit INMXZ03(R) would receive control.

If RACF® is installed, and if you are using security labels, exit INMXZ03 receives control after INMXZ21R.

Errors during log processing do not normally terminate command processing. Instead, the command sets a return code of 4, indicating that failure occurred but the transmission was successful. If the exit gives a non-zero return code, TRANSMIT does not terminate processing, but sets a return code of 4, indicating that the logging function encountered an error.