Allocate file resources

Resources are those parts of the server that are required by a job or task, including main storage, devices, the processing unit, programs, files, libraries, and folders. When you write a high-level language program, you should be aware of what resources the server has allocated for each file type.

Normally, the server will perform the allocation whenever a requested operation requires it. For example, the server allocates resources for each file that is used in a program when the file is opened.

To ensure that all of the resources that are needed by a program are available before the program is run, you can use the Allocate Object (ALCOBJ) CL command in the job before you run the program. In particular, the ALCOBJ command can allocate database files and most devices.

• Overview of file resource allocation
  When a high-level language program uses a file, several operations require that the server allocate the resources that are needed to perform that operation. The server generally does this to ensure that multiple users do not use the file in conflicting ways.
• File resources that must be allocated
  The file resources that the server must allocate depend on the type of file and the operation.
• How the server allocates resources
  When it allocates resources, the server waits for a predefined time if the resources are not immediately available. If the resources do not become available within the time limit, the server generates an error.