Subtasking

The nfstasks(n,m,o,t,u) site attribute specifies the number of server threads (subtasks) to initiate on startup, where:

n: is the number of threads started to handle asynchronous operations (z/OS MVS data set access) and short duration synchronous operations (SAF calls).
m: is the number of threads which handle z/OS UNIX requests. Increase this value if your server requires many parallel z/OS UNIX accesses.
o: is the number of threads that handle longer duration synchronous operations (concurrent NFS server recall requests.) Increase this value if your server supports lots of active recall operations.
t: is the number of transport threads dedicated to receiving TCP requests. If a large number of concurrent TCP requests are expected and the n,m values have already been increased to handle the expected request processing workload but the requests still seem to be taking excessively long to complete, then this value should be increased to relieve any possible bottleneck in the request receive processing.
u: is the number transport threads dedicated to receiving UDP requests. If a large number of concurrent UDP requests are expected and the n,m values have already been increased to handle the expected request processing workload but the requests still seem to be taking excessively long to complete then this value should be increased to relieve any possible bottleneck in the request receive processing.

If nfstasks(n,m) is specified, then the valid value range for n is from 4 to 99 and for m is from 4 to 100. The sum of n and m must be less than or equal to 100. If nfstasks(n,m,o) is specified, then the valid value range for n is less than or equal to 99 and for m is less than or equal to 100. The valid value range for o is less than or equal to 99. The sum of m plus o must be less than or equal to 100.

The absolute and relative value of n and m should be tuned for the expected system usage. If z/OS MVS data sets will be accessed, primarily, then n should be relatively high. If z/OS UNIX files will be accessed, primarily, then m should be relatively high. The absolute value of these will influence the amount of system resources consumed (higher values will make more system resources available to process NFS requests.

Based on system resources available below the 16 Mb line, the maximum n value may not be achievable. The precise maximum value will be system configuration dependent. If an 80A or 878 Abend is experienced during NFS server startup, use a smaller value for n.

When nfstasks(n,m) is specified, m represents both the processes for z/OS UNIX as well as the long duration synchronous operations. It is better to use the nfstasks(n,m,o) format to have better granularity of control and have the ability to specify a higher number of z/OS UNIX processes to handle more z/OS UNIX operations.

Based on system resources available below the 16 Mb line, the maximum n + o value may not be achievable. The precise maximum value will be system configuration dependent. If an 80A or 878 Abend is experienced during NFS server startup, use a smaller value for n + o.