Threadsafe classification

The threadsafe classification indicates whether a command is threadsafe. Each command has a threadsafe classification.

The three types of threadsafe classifications are as follows:

• Threadsafe: Yes

  This classification indicates that you can safely call the command simultaneously in multiple threads without restrictions. This classification also indicates that all functions called by this command are threadsafe.

• Threadsafe: Conditional

  This classification indicates that not all functions provided by the command are threadsafe. The Restrictions section of the command provides information relating to thread safety limitations. Many commands are classified conditionally threadsafe because either some underlying system support is not threadsafe or the command can cause an exit point to be called.

• Threadsafe: No

  This classification indicates that the command is not threadsafe and should not be used in a multithreaded program. While some thread unsafe commands may deny access, most thread unsafe commands do not. A diagnostic message, CPD000D, may be sent to the job log to indicate that a non-threadsafe command has been called. Whether or not the diagnostic message CPD000D is sent to the job log depends on the "multithreaded job action" attribute of the command; that attribute can be determined by using the Display Command (DSPCMD) command. The possible values and actions are:

  • *SYSVAL - Action is based on system value QMLTTHDACN
  • *RUN - Command runs. No messages are sent.
  • *MSG - Diagnostic message CPD000D is sent to the job log. The command runs.
  • *NORUN - Diagnostic message CPD000D is sent to the job log, and escape message CPF0001 is sent. The command does not run.

  If the command is run, the results are unpredictable.