DTLLOG DD Usage Considerations

You must specify the DTLLOG DD statement for the following purposes:
To write initial startup messages
To write messages if PowerExchange encounters an error allocating or writing to alternative log data sets
The DTLLOG DD statement can point to a permanent data set or to a SYSOUT data set. Informatica recommends that you specify SYSOUT=* to help safeguard against failures with alternative log files and to prevent the out-of-space conditions.
Unless you specify a DTLLOG
nn
DD statement in the JCL, PowerExchange dynamically allocates alternative log files.
To prevent loss of PowerExchange log and trace information, use unique data set names for each PowerExchange job that have DTLLOG
nn
DD statements.
If you use a GDG for alternative logging, add a single DTLLOG01 DD statement that specifies GDG(0) in the JCL.
PowerExchange jobs and started tasks that write to alternative log files include the PowerExchange Listener, PowerExchange Condense, PowerExchange Agent, and netport jobs. The Adabas, IDMS, and IMS log-based ECCRs and the Datacom table-based ECCR can also use alternative log files.
The PowerExchange Logger, batch VSAM ECCR, CICS/VSAM ECCR, and IMS synchronous ECCR do not write messages to the PowerExchange message log or alternative log files.

How PowerExchange Determines the Starting Alternative Log File

Lists each alternative log file to use
Reads the timestamp record at the beginning of each alternative log file
Opens the alternative log file according to the TRACING statement APPEND setting:
If TRACING APPEND=Y, the alternative log file with the most recent time stamp is opened in append mode.
If TRACING APPEND=N, the alternative log file with the most oldest time stamp is opened in write mode so that its contents are overwritten.