QUEUE appends the string resulting from expression to the tail of the external data queue. That is, it is added FIFO (First In, First Out). (See Chapter 14, Input and Output Streams for a discussion of Rexx input and output.)
If you do not specify expression, a null string is queued.
Example 2.36. Instructions - QUEUE
a="Toft"
queue a 2 /* Enqueues "Toft 2" */
queue /* Enqueues a null line behind the last */
The QUEUED built-in function (described in Section 7.4.48, “QUEUED”) returns the number of lines currently in the external data queue.