You can request that the Transaction dump be written to a data set that is either pre-allocated or automatically allocated. To request a pre-allocated data set, specify the DDNAME parameter that identifies a data set that contains sufficient space in one or more extents for the entire dump to be written. If you don't provide a large enough data set, you will receive a partial dump. To request automatic allocation, specify the DSN and DSNAD parameters to diminish the exposure that the dump is truncated because of data set space constraints. Automatic allocation is done to SYSALLDA. When using DSN or DSNAD, the maximum dump size is 2 GB. To collect data beyond that, use the &DS symbol at the end of the pattern. Then, the dump data is split across multiple data sets. DDNAME does not have the 2GB size restriction.