TSSMAINS receives U1520 abend VSAMFILE FILE ALREADY INITIALIZED
VSAMFILE INITIALIZATION FAILED.
Why does this occur?
The VSAMFILE FILE ALREADY INITIALIZED is issued when TSSMAINS been run more than once (unsuccessfully or successfully) using the same VSAMFILE DD dataset.
The TSSMAINS can only run once using the same VSAMFILE DD dataset.
If there is a need to run it again, must delete the VSAMFILE dataset and recreate it before running TSSMAINS again.