z/OS Version 1 Release 10
The "query_queue_time" column indicates that the query is waiting in the queue for a WLM slot to execute. ... For more information, see Step 1: Override the concurrency level using wlm_query_slot_count.
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The wlm_query_slot_count configuration setting is valid for the current session only. If that session expires, or another user runs a query, the WLM configuration is used.