IGD17284I

Explanation
In a 'best-fit' request for allocation of a data
set, this particular Storage Group was tried but did not have enough
space. Allocation will be attempted on another Storage Group or, if
there is no other selected Storage Group, the allocation will fail.
In
the message text: sg
The rejected storage group
dsname
The The data set name

System action
The SMS VTOC Data Set Services request fails.

Programmer response
Application Programmer Response: Correcting
this situation may require that the ACS routines be modified to select
different Storage Groups or make more space available on the Storage
Groups that were selected.

Source
Data Facility Product (DFSMS)