Improved Control Interval Access

Improved control interval access (ICI) is faster than normal control interval access; however, you can only have one control interval scheduled at a time. Improved control interval access works well for direct processing.

To use ICI, you have to specify user buffering (UBF), which provides the option of specifying improved control interval access:

   ACB      MACRF=(CNV,UBF,ICI,...),...

You cannot load or extend a data set using ICI. Improved control interval processing is not permitted for extended format data sets.

A processing program can achieve the best performance with improved control interval access by combining it with SRB dispatching. SRB dispatching is described in z/OS MVS Programming: Authorized Assembler Services Guide and Operating in SRB or Cross-Memory Mode.