Job variables (JVs) are storage areas which enable the exchange of information both between individual jobs and between jobs and the operating system. They have a name and a value. This value may be used to control jobs and programs. For instance, the user may specify that job B is not to be started until job A has set the predefined job variable V1 to the value “START B”. The functions required for working with job variables are provided as COBOL statements or on the command or macro level.
The user can
generate
modify
interrogate
delete
job variables or instruct the operating system to set a monitoring job value accordingly when the status of a job or program changes. The user can reference the monitored job in commands by using a job variable instead of by specifying the TSN. Job variables thus provide the user with a tool enabling flexible job control. They offer a simple way of defining dependencies between jobs. Conditional job control gives the user the option of making the execution of certain actions (e.g. job initiation) dependent on changes in the values of certain predefined job variables. This is implemented by means of commands to the operating system which are executed only when, or not until, the user-defined event occurs (job variable assumes a particular value). These events can be used in the same way as user or job switches for conditional branches within command sequences and for synchronous waiting. In contrast to switches (state ON or OFF), job variables can have a number of different possible values, combinations of which can also be given in conditional expressions.
Asynchronous waiting is also possible (a command sequence is not executed until the event occurs and only then is processing interrupted).
The functions described below are available both on a single-computer system and in a BS2000 cluster.