Allocating the Trace Data Set

The trace data set must have the following characteristics:

ddname -- CHSTRACE
logical record length -- 80
format -- fixed or fixed block

You can create the trace data set with the following command:

ALLOCATE FILE(CHSTRACE) DA('data_set_name') NEW LRECL(80) RECFM(F)

To make the trace data set available to an MVSSERV user, allocate the existing data set in the user's logon procedure, or in a CLIST, REXX exec, or ISPF dialog that issues MVSSERV for the user. Users must have their own trace data sets.

In a logon procedure, you can use the following JCL:
```
//CHSTRACE DD DSN=data_set_name,DISP=OLD
```
In a CLIST, REXX exec, or ISPF dialog, you can use the following command:
```
ALLOCATE FILE(CHSTRACE) DA('data_set_name') OLD
```

For more information about the MVSSERV trace parameters and syntax, refer to Testing and Diagnosis.

Note: Use of the trace parameters may affect MVSSERV performance. Therefore, your installation may decide not to use the MVSSERV trace parameters for regular production work. However, for testing or diagnosing servers, or requesting diagnosis help from IBM® service personnel, use MVSSERV with the trace data set and the parameter TRACE or IOTRACE.