Spool volumes are added either at a cold start or dynamically through use of operator commands (refer to z/OS JES2 Commands for specific command usage). You can define a maximum of 253 spool volumes to JES2 at any one time. If the dynamic addition of another spool volume is attempted (thereby exceeding the maximum of 253 spool volumes) the command will be ignored, the volume will not be added, and JES2 issues message $HASP411 to the operator.

If however, the maximum of 253 spool volumes is exceeded during a cold start, JES2 issues a message informing the operator that more spool volumes were found than expected from the SPOOLNUM= specification on the SPOOLDEF initialization statement. Then, the operator can determine whether to end initialization. To display the contents and count the number of defined spool volumes the operator can issue the $D SPL, ALL command. All volumes listed (to include those in draining status) should be included in your count. Only after such volumes are completely drained are they considered undefined to JES2.

The operator can issue the $S SPL command to add (and format) a new spool volume or return an inactive volume to the configuration. The SPOOL data set on the new SPOOL volume can be pre-allocated or created by JES2 by using the SPACE= parameter on the $S SPL command. During the addition phase of a spool volume, other processing within the system continues normally.