CICS Introduction

Code Example

## CICS Introduction

Customer Information Control System (CICS) is IBM's transaction processing system.

### What is CICS?
- Online transaction processing (OLTP)
- Handles thousands of transactions/second
- Manages terminals and programs
- Provides services for applications

### Key Concepts

| Term | Description |
|------|-------------|
| Transaction | Unit of work (4-char ID) |
| Task | Instance of running transaction |
| Terminal | User interaction point |
| Program | Application code |

### CICS Services
1. **Task Management** - Create/manage tasks
2. **Storage Management** - Memory allocation
3. **Program Control** - Load/execute programs
4. **File Control** - VSAM access
5. **Terminal Control** - Screen I/O
6. **Temp Storage** - Temporary data

### Transaction Processing
1. User enters transaction ID
2. CICS locates program
3. Program executes
4. Response sent to terminal