When CA Allocate does the add volume operation at EOV, does that use space in TIOT ?

Document ID : KB000044686
Last Modified Date : 14/02/2018
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Question:

When CA Allocate does the add volume operation at EOV, does that use space in TIOT ?

Answer:

At end-of-volume (EOV) time for a SMS-managed data set, CA Allocate checks for a ‘DVC’ value if a DATACLAS is present. If there is a ‘DVC’ value, CA Allocate will consider these to be ‘candidate’ volumes, and CA Allocate does not need to get involved with adding a volume to the data set. 

Allocating a dataset with a DATACLAS that has a ‘DVC’ value will create a larger ‘TIOT’ control block in order to handle the possible expansion of the dataset onto multiple volumes. 

If a dataset is allocated without a DATACLAS that has a ‘DVC’ value, and no other candidate volumes, then, at EOV time, when CA Allocate adds a volume, CA Allocate will dynamically expand the TIOT in order to accommodate the new volume added. CA Allocate will do this dynamic expansion for each volume it adds. But it is important to note that CA Allocate only expands the TIOT by the amount necessary to add the one volume.