IMS Spool API design

The IMS Spool API design provides the application program with the ability to create print data sets on the JES spool using the standard DL/I call interface.

The functions provided are:

• Definition of the data set output characteristics
• Allocation of the data set
• Insertion of lines of print into the data set
• Closing and deallocation of the data set
• Backout of uncommitted data within the limits of the JES interface
• Assistance in controlling an in-doubt print data set

The IMS Spool API support uses existing DL/I calls to provide data set allocation information and to place data into the print data set. These calls are:

• The CHNG call. This call is expanded so that print data set characteristics can be specified for the print data set that will be allocated. The process uses the alternate PCB as the interface block associated with the print data set.
• The ISRT call. This call is expanded to perform dynamic allocation of the print data set on the first insert, and to write data to the data set. The data set is considered in-doubt until the unit of work (UOW) terminates. If possible, the sync point process deletes all in-doubt data sets for abending units of work and closes and deallocates data sets for normally terminating units of work.
• The SETO call. This is a call, SETO (Set Options), introduced by this support. Use this call to create dynamic output text units to be used with the subsequent CHNG call. If the same output descriptor is used for many print data sets, the overhead can be reduced by using the SETO call to prebuild the text units necessary for the dynamic output process.