Restrictions on the Use of Checkpoints

There are certain restrictions on the features that can be in use by a task when it is checkpointed. These restrictions apply to both programmatically initiated checkpoints and operator initiated checkpoints. If any of these features are in use, they prevent a successful checkpoint. If a checkpoint fails, the task continues normally, but no checkpoint files are created.

The following restrictions apply to the tasking environment of the checkpointed task:

  • The task must have been initiated by a RUN statement in a WFL job. The checkpointed task must be the only in-use offspring of the WFL job at the time the checkpoint is invoked.

  • The task cannot be a remote task. That is, it must not be initiated on a BNA host system other than that on which the job is running.

  • The task must not have any offspring at the time of the checkpoint. However, the task can have offspring at earlier, or later, points in its execution.

A checkpoint cannot be invoked from within the following types of procedures:

  • An imported library procedure. The checkpoint cannot take place if an imported library procedure is anywhere in the process stack. However, the checkpoint can be invoked if the user process is merely linked to a library.

  • A SORT input or output procedure. (SORT provides its own restart capability; refer to the System Software Utilities Operations Reference Manual.)

Several types of files cannot be open at the time of the checkpoint. However, the process can close these files, take a checkpoint, and then reopen the files and continue to use them. The following are the restricted types of files:

  • Direct files

  • Disk files whose DUPLICATED attribute value is TRUE

  • Files whose FILESTRUCTURE attribute value is not ALIGNED180

  • ISAM files

  • Multireel unlabeled tape files

  • ODT files

  • Remote files

  • Port files

  • Reversed tape files

Some restrictions also apply to printer output. All open printer files must be backup files, and have a PRINTDISPOSITION file attribute value of EOJ or DONTPRINT. In addition, the BDBASE option of the OPTION task attribute cannot be set.

The process cannot have an Enterprise Database Server database open at the time of the checkpoint.

No direct arrays can be in the process stack at the time of the checkpoint. A direct array can be declared in a procedure in the program. However, the procedure must not have been entered, or must have been entered and exited, before the checkpoint.

The checkpoint file cannot be created if doing so would cause the user's file usage on a family to exceed the limits enforced for the user by the disk resource control (DRC) system. For information about the disk resource control system, refer to the System Administration Guide and the System Operations Guide.

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