Using the following keywords in the JCL section of a TP profile affects performance:

• The system variable &SYSUID in a data set name causes performance degradation.
• JCLLIB statements also cause performance degradation.
• Using DISP=OLD for data sets accessible by more than one user can cause contention and degrade performance. If possible, use DISP=SHR instead.
• When using temporary data sets, avoid the use of &&DSNAME wherever possible. Specifying no data set name for temporary data sets allows the system to create a unique name and avoids contention between transaction programs for the same data set name.