When analyzing a stand-alone dump for an enabled wait condition, check the status of the input/output requests. A display of the IOS control block and any active UCBs can help determine what was happening when the system entered the wait state.
In Figure 1, the HOTIO field indicates that a solicited interrupt has completed with other than DCC-3 because the last time HOT-I/O detection was called. Note also that the IOQF and IOQL fields are identical, indicating that the first and last request for this device is the same.
* * * ACTVUCBS Processing * * *
UCB AT 00F8B798: DEVICE 001; SUBCHANNEL 0001
UCBPRFIX: 00F8B768
-0030 RSTEM.... 00 RSV...... 08 MIHTI.... 40
-002D HOTIO.... 40 IOQF..... 00F7BC00 IOQL..... 00F7BC00
-0024 SIDA..... 0001 SCHNO.... 0001 PMCW1.... 2888
-001E MBI...... 0000 LPM...... 80 RSV...... 00
-001A LPUM..... 80 PIM...... 80 CHPID.... 21000000
-0014 00000000 LEVEL.... 01 IOSF1.... 00
-000E MIHCT.... 0000 LVMSK.... 00000001 LOCK..... 00000000
-0004 IOQ...... 00F7BC00