You must allocate space in tracks, cylinders, records, kilobytes, or megabytes for a linear data set.

When you define a linear data set, you can specify a control interval size of 4096 to 32␠768 bytes in increments of 4096 bytes. If not an integer multiple of 4096, the control interval size is rounded up to the next 4096 increment. The system chooses the best physical record size to use the track size geometry. For example, if you specify CISIZE(16384), the block size is set to 16␠384. If the specified BUFFERSPACE is greater than 8192 bytes, it is decremented to a multiple of 4096. If BUFFERSPACE is less than 8192, access method services issues a message and fails the command.