SMB: Add _BPXK_UNUSEDTASKS=KEEP to the DFSCNTL environment file

Description

Before z/OS V2R2 and without the z/OS UNIX PTF for APAR OA39909, which changed threading behavior, SMB users did not have to specify that medium weight threads were to be kept. As of APAR OA39909 and z/OS V2R2, SMB users must keep the original threading behavior by setting the _BPXK_UNUSEDTASKS=KEEP environment variable, as described in DFS SMB APAR OA45175.

Table 1 provides more details about this migration action. Use this information to plan your changes to the system.

Table 1. Information about this migration action
Element or feature: Server Message Block (SMB) support of the IBM z/OS Distributed File Service base element.
When change was introduced: z/OS V2R2, and z/OS V1R13 and V2R1 with PTFs for APARs OA39909 and APAR OA43472 installed.
Applies to migration from: z/OS V2R1 and z/OS V1R13, both without APARs OA39909 and APAR OA43472 installed.
Timing: After the first IPL of z/OS V2R2.
Is the migration action required? Yes, if you use SMB.
Target system hardware requirements: None.
Target system software requirements: None.
Other system (coexistence or fallback) requirements: None.
Restrictions: None.
System impacts: Failure to implement this migration action prevents the DFS/SMB server from starting or restarting because z/OS UNIX System Services issues a SIGKILL to the DFS/SMB server. The following symptoms might be encountered if this migration action is not implemented: 
DFSKERN S069 422 SA03 
BPXP023I IOEP01100I 
IOEP01123A RESTART SIGKILL
or
SYSTEM ABEND S069 - REASON CODE 04
Related IBM® Health Checker for z/OS® check: None.

Steps to take

Because SMB is dependent on the threading model that was in effect before the PTFs for APAR OA39909 and APAR OA43472 were installed, you need to take the following steps:
  1. To allow SMB to use the original threading behavior, add the environment variable _BPXK_UNUSEDTASKS=KEEP to the SMB DFSCNTL environment file, which is typically found in the /opt/dfslocal/home/dfscntl/envar directory.
  2. If SMB is started, it must be stopped and restarted using the C DFS and S DFS commands.

After you complete the steps, SMB will use the original threading behavior that was in place prior to the PTF for APAR OA39909.

Reference information

For more information, see the following references:
Parent topic: Distributed File Service actions to perform after the first IPL of z/OS V2R2