Migration and the API

When you consider moving an application to TXSeries®, compare the CICS® application programming interface (API) commands that the application uses with those that TXSeries supports. TXSeries supports only a subset of the CICS API commands. Note that some API commands have different sets of options on TXSeries from the options that are on other CICS products.

Overview of migration and the API

If you need to migrate an application program from your existing CICS system that uses API commands or options that TXSeries does not support, you must do one of the following tasks:

  • Modify the application to use API commands that TXSeries supports.
  • Allow the application to coexist with TXSeries by continuing to run the application in your existing CICS system.

For a list of the API commands and options that CICS supports, see CICS API command reference. Differences between the TXSeries-supported API and that which is supported by other CICS family members are given in CICS Family: API Structure.

If you do not remove, from an application program, the API commands or options that TXSeries does not support, you can use the CICS command language translator to highlight the unsupported commands or options as errors. This method is a quick way of finding out whether an existing program runs under TXSeries without conversion. Conversely, this method helps you to accurately estimate the effort that you require to migrate an application program to the TXSeries API.

In all CICS products, you can place command options in any sequence in a command, as long as you place the command identifier first. CICS family products interpret the scope of a command identifier differently: some products consider only the first word to be significant (such as HANDLE) while others, of which TXSeries is one, consider one or more words to be significant (such as EXEC CICS HANDLE CONDITION). Therefore, HANDLE RESP CONDITION and EXEC CICS SET FILE NOHANDLE OPEN are invalid in TXSeries.

You can tell how many words are considered to be significant in a command identifier by looking at its title in CICS API command reference.