You probably won't need Compare and Swap (CMPSWP) often, but when you do, you'll appreciate its high level of performance.
By Bruce Vining
There are some types of data, an invoice number for instance, that have characteristics such that the "next" value...
• needs to be generated concurrently by several jobs,
• needs to be unique within the application,
• and is generally sequential in nature.
This type of data requirement historically has been satisfied with approaches such as using a data area (*DTAARA) to store and share the next available invoice number across the users of the application. While *DTAARAs work fine for this type of application, other options can provide this level of function at a much higher level of performance. One such option is the Compare and Swap (CMPSWP) Machine Interface (MI) instruction.
Automating reports and distributing documents electronically is both good for the planet and great for the bottom line.
By Chris Smith
We don't have detailed demographics on all our MC Press Online readers, but my guess is there aren't too many who were working on computers in the early 1960s when IBM coined the term "spool file."
The acronym stands for Simultaneous Peripheral Operation On-Line (SPOOL), but folklore has it that the name actually was conceived after the term "spool" came into widespread use, since a spool is what is used to wind magnetic tape.
