THSIZE – Thread Size

To improve the processing performance, this Natural profile parameter can be used to define the size of a storage thread for running in z/OS or z/VSE batch mode or under TSO.

Possible settings 256 - 2097151 or 0 Thread size in KB.
Default setting 0 No thread used.
Dynamic specification yes  
Specification within session no  


  1. This Natural profile parameter does not have any effect on other environments where threads are used already, for example, server environments.
  2. The storage thread is allocated during session start. Natural tries to satisfy all storage requests (GETMAIN/FREEMAIN) within this thread instead of passing it to the operating system. The thread must be large enough to contain all fixed size buffers. If the thread is full, variable sized buffers may be allocated outside the thread, provided that profile parameter OVSIZE allows this.
  3. The profile parameter THSIZE is ignored if it is specified in a parameter string activated by a SYS or PROFILE profile parameter or in an alternative Natural parameter module (as specified with the PARM profile parameter).
  4. If Natural zIIP Enabler is installed and active (z/OS batch and TSO only), an appropriate setting of THSIZE can reduce the number of switches into TCB mode, because of the reduced number of physical GETMAINs. The same applies if profile parameter WPSIZE is used.