A temporary storage queue that has only one record can be treated as a
single unit of data that can be accessed using its symbolic name. Using temporary
storage control in this way provides a typical scratch-pad capability. This type of storage should be accessed using the READQ TS command with
the ITEM option; not doing so may cause the ITEMERR condition to be raised.
In general, temporary storage queues of more than one record should be
used only when direct access or repeated access to records is necessary; transient
data control provides facilities for efficient handling of sequential data sets.
Some uses of temporary storage queues are:
- Terminal paging
- A task could retrieve a large master record from a direct-access data set,
format it into several screen images (using BMS), store the screen images
temporarily in auxiliary storage, and then ask the terminal operator which "page"
(screen image) is desired. The application programmer can provide a program
(as a generalized routine or unique to a single application) to advance page
by page, advance or back up a relative number of pages, and so on.
- A suspend data set
- Suppose a data collection task is in progress at a terminal. The task
reads one or more units of input and then allows the terminal operator to
interrupt the process by some kind of coded input. If not interrupted, the
task repeats the data collection process. If interrupted, the task writes
its incomplete data to temporary storage and terminates. The terminal is now
free to process a different transaction (perhaps a high-priority inquiry).
When the terminal is available to continue data collection, the operator initiates
the task in a "resume" mode, causing the task to recall its suspended
data from temporary storage and continue as though it had not been interrupted.
- Preprinted forms
- An application program can accept data to be written as output on a
preprinted form. This data can be stored in temporary storage as it arrives.
When all the data has been stored, it can first be validated and then transmitted
in the order required by the format of the preprinted form.
[[ Contents Previous Page | Next Page Index ]]